SLI Scaling and Quality Investigation
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[center]Introduction[/center]


[b]Introduction[/b]:

[b]
[i] Why isnt my performance going up?[/i]

[i] Do I need a large monitor to take advantage of SLI? [/i]

[i] If your CPU limited can you still benefit from SLI?[/i][/b]

I am often asked these questions when I am asked to troubleshoot or makes suggestions for people with SLI setups. While there is no easy answer I have prepared this guide to help people understand performance bottlenecks and how to aleviate them. To perform these tests I have decided to use a medium range SLI setup consisting of two 7900GT's and midrange gaming resolutions to illustrate the performance characteristics of SLI in CPU bottleneck scenarios.

[b]
Athlon 64 3800+ @ 2.4 Ghz (Stock)
Asus A8N32 SLI Deluxe
MSI Geforce 7900GT Vivo HD SLI @ 500/1530 ((Stock))
2 Gigs DDR400 Memory
91.47 Nvidia forceware Drivers
[/b]

[b]Scaling[/b]: Understanding SLI scaling is very important. Nvidia provides utilities which allow you to verify the scaling of your multi GPU solution. To access them you'll want to use the old control panel and visit the SLI section in the control panel and enable Show SLI Load Balancing.

[center]
[img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/showgpuload.jpg[/img]
[/center]

It is important to recognise the difference between [url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/lowscaling.jpg"]Low SLI Scaling[/url] and [url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/goodscaling.jpg"]Good SLI Scaling[/url] . Low SLI scaling generally just means you are CPU limited. Higher resolutions and higher levels of AA and AF can mean the difference between good scaling and bad scaling. The difference between examples of [url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/lowscaling.jpg"]Low SLI Scaling[/url] and [url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/goodscaling.jpg"]Good SLI scaling[/url] in this case are that of no anti aliasing or anistropic filtering in comparison to 8x antialiasing and 16x anisotropic filtering. The scene doing the higher levels of AA and AF inherantly requires more GPU workload decreasing the amount of idle time between GPUS.

[b][i] So which anti aliasing settings do I use? [/b][/i]

This will be very dependent on alot of things. But here's a quick list of things you should consider. The AA modes discussed in this investigation will cover midrange resolutions.

1) Your current SLI Setup. Are you running Geforce 6600GT in SLI or Geforce 7900GTX SLI configuration? The amount of processing power available to you is going to greatly depend on how bottlenecked you might end up in some software. Geforce 7900/7600 hardware and above is more efficient than older Nvidia hardware when running SLI AA modes.

2) Your current resolution. Higher level resolutions will inherantly be more GPU limited than lower resolution modes.

3) How GPU limited the current software is. Some software is much more GPU limited than others. Playing Quake 3 Arena for instance will be very CPU limited on a 7900GTX SLI setup while FEAR will end up more bound by the graphic subsystem. To determine the amount of graphic workload your SLI cards are under use the [url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/showgpuload.jpg"]GPU Load Balancing Function[/url] to determine your level of GPU scaling.

[b]
[center]The AA Modes[/center][/b]

[b]4xAA[/b]: 4xAA is the baseline for which most computers are judged these days. 4x rotated grid multisampling produces excellent results for the performance range its intended. However despite its effectiveness it often ends up CPU limited on modern SLI setups.

[img]http://www.3declipse.com//images/stories/ChrisRay/AAcompare/4xaa.jpg[/img]

[b]8xS:[/b] 8xS is a hybrid mode of multisampling and supersampling. It effectively
takes two 4x multisamples and passes them through the same texture twice. The
result is a 1x2 Ordered Grid Supersampling component which can also sharpen textures and anti alias alpha textures. This mode can be slightly framebuffer intensive. Due its supersampling nature it can require a significant amount of fillrate. Something SLI setups will generally have plenty to spare. This mode is available to all Nvidia users from the Geforce 6 and up.

[img]http://www.3declipse.com//images/stories/ChrisRay/AAcompare/8xseer.jpg[/img]

[b]SLI 8x[/b]: SLI 8xAA is a unique solution available to SLI users. This mode takes 4x multisampling and combines it between the two GPUs to output into a very framebuffer efficient 8xAA mode. The supersampling component is slightly offset to a rotated grid pattern which should make it sample texels at a vertical angle better than 8xS. However its sampling position may allow for 8xS to sample slightly better in some circumstances.

[img]http://www.3declipse.com//images/stories/ChrisRay/AAcompare/sli8xsample.jpg[/img]

[b]16xS[/b]: 16xS is hybrid mode that is unsupported by Nvidia. In order to enable it you will need a program such as [url="http://www.nhancer.com/"]Nhancer[/url] or [url="http://www.guru3d.com/rivatuner/"]Rivatuner[/url]. The purpose of including this mode is mostly educational. However it can be useful for comparison sake as well. This mode consists of 2x2 ordered grid supersampling. Each supersample takes a 4x multisample. 4x ordered grid supersampling can be very effective at cleaning up speculiar aliasing. However this AA mode requires a massive amount of framebuffer space which can bring 256 meg cards to their knees. It does however bring a significant quality improvement over the 8xS mode.

[img]http://www.3declipse.com//images/stories/ChrisRay/AAcompare/16xseer.jpg[/img]

[b]SLI 16x[/b]: SLI 16x mode is another mode unique to SLI user. It does 8xS on each GPU and combines them for the final output. The result is a framebuffer efficient 16x anti aliasing mode. The mode also containts 4x supersampling with a slight offset making it slightly rotated grid. For the most part SLI16x will offer equivalent quality to that of 16xS.

[img]http://www.3declipse.com//images/stories/ChrisRay/AAcompare/sli16xsample.jpg[/img]
Introduction






Introduction:





Why isnt my performance going up?



Do I need a large monitor to take advantage of SLI?



If your CPU limited can you still benefit from SLI?




I am often asked these questions when I am asked to troubleshoot or makes suggestions for people with SLI setups. While there is no easy answer I have prepared this guide to help people understand performance bottlenecks and how to aleviate them. To perform these tests I have decided to use a medium range SLI setup consisting of two 7900GT's and midrange gaming resolutions to illustrate the performance characteristics of SLI in CPU bottleneck scenarios.





Athlon 64 3800+ @ 2.4 Ghz (Stock)

Asus A8N32 SLI Deluxe

MSI Geforce 7900GT Vivo HD SLI @ 500/1530 ((Stock))

2 Gigs DDR400 Memory

91.47 Nvidia forceware Drivers





Scaling: Understanding SLI scaling is very important. Nvidia provides utilities which allow you to verify the scaling of your multi GPU solution. To access them you'll want to use the old control panel and visit the SLI section in the control panel and enable Show SLI Load Balancing.





Image





It is important to recognise the difference between Low SLI Scaling and Good SLI Scaling . Low SLI scaling generally just means you are CPU limited. Higher resolutions and higher levels of AA and AF can mean the difference between good scaling and bad scaling. The difference between examples of Low SLI Scaling and Good SLI scaling in this case are that of no anti aliasing or anistropic filtering in comparison to 8x antialiasing and 16x anisotropic filtering. The scene doing the higher levels of AA and AF inherantly requires more GPU workload decreasing the amount of idle time between GPUS.



So which anti aliasing settings do I use?



This will be very dependent on alot of things. But here's a quick list of things you should consider. The AA modes discussed in this investigation will cover midrange resolutions.



1) Your current SLI Setup. Are you running Geforce 6600GT in SLI or Geforce 7900GTX SLI configuration? The amount of processing power available to you is going to greatly depend on how bottlenecked you might end up in some software. Geforce 7900/7600 hardware and above is more efficient than older Nvidia hardware when running SLI AA modes.



2) Your current resolution. Higher level resolutions will inherantly be more GPU limited than lower resolution modes.



3) How GPU limited the current software is. Some software is much more GPU limited than others. Playing Quake 3 Arena for instance will be very CPU limited on a 7900GTX SLI setup while FEAR will end up more bound by the graphic subsystem. To determine the amount of graphic workload your SLI cards are under use the GPU Load Balancing Function to determine your level of GPU scaling.





The AA Modes




4xAA: 4xAA is the baseline for which most computers are judged these days. 4x rotated grid multisampling produces excellent results for the performance range its intended. However despite its effectiveness it often ends up CPU limited on modern SLI setups.



Image



8xS: 8xS is a hybrid mode of multisampling and supersampling. It effectively

takes two 4x multisamples and passes them through the same texture twice. The

result is a 1x2 Ordered Grid Supersampling component which can also sharpen textures and anti alias alpha textures. This mode can be slightly framebuffer intensive. Due its supersampling nature it can require a significant amount of fillrate. Something SLI setups will generally have plenty to spare. This mode is available to all Nvidia users from the Geforce 6 and up.



Image



SLI 8x: SLI 8xAA is a unique solution available to SLI users. This mode takes 4x multisampling and combines it between the two GPUs to output into a very framebuffer efficient 8xAA mode. The supersampling component is slightly offset to a rotated grid pattern which should make it sample texels at a vertical angle better than 8xS. However its sampling position may allow for 8xS to sample slightly better in some circumstances.



Image



16xS: 16xS is hybrid mode that is unsupported by Nvidia. In order to enable it you will need a program such as Nhancer or Rivatuner. The purpose of including this mode is mostly educational. However it can be useful for comparison sake as well. This mode consists of 2x2 ordered grid supersampling. Each supersample takes a 4x multisample. 4x ordered grid supersampling can be very effective at cleaning up speculiar aliasing. However this AA mode requires a massive amount of framebuffer space which can bring 256 meg cards to their knees. It does however bring a significant quality improvement over the 8xS mode.



Image



SLI 16x: SLI 16x mode is another mode unique to SLI user. It does 8xS on each GPU and combines them for the final output. The result is a framebuffer efficient 16x anti aliasing mode. The mode also containts 4x supersampling with a slight offset making it slightly rotated grid. For the most part SLI16x will offer equivalent quality to that of 16xS.



Image

#1
Posted 09/08/2006 03:30 AM   
[b][center]Performance and Quality [/b][/center]

[b]Performance[/b]: So what of Performance and Quality? Now that we have gone over the AA settings available to us we'll now get to see them in action. The next section of the investigation covers performance and quality of these AA settings through 5 well known games. All games were run in High Quality mode with anisotropic filtering set to 16x. All my benches are done in game via fraps.


[b][center]Everquest 2 [/b][/center]


[b] Everquest 2[/b]: Everquest 2 is a fairly new MMORPG. It is well known for being a very performance taxing application. It can feature a moderate amount of CPU and GPU limitation depending on your setup. SLI Configurations are often quickly limited by the CPU in this game.

[b] Quality:[/b]

[b]4xAA[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/EQ2/4xaa.png"]http://www.3declipse.com//images/stories/C...ou/EQ2/4xaa.png[/url]

[b]8xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/EQ2/8xs.png"]http://www.3declipse.com//images/stories/C...you/EQ2/8xs.png[/url]

[b]SLI 8x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/EQ2/sli8x.png"]http://www.3declipse.com//images/stories/C...u/EQ2/sli8x.png[/url]

[b]16xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/EQ2/16xs.png"]http://www.3declipse.com//images/stories/C...ou/EQ2/16xs.png[/url]

[b]SLI 16x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/EQ2/sli16x.png"]http://www.3declipse.com//images/stories/C.../EQ2/sli16x.png[/url]

[b]Note:[/b] These shots are not 100% identical due the weather pattern changes in MMORPGs, However still effectively demonstrate the quality differences.

[center][img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/EQ2/eq2aa.png[/img]
[/center]

[b]Performance thoughts[/b]: Clearly Everquest 2 is limited by the CPU to a good degree in this map. Increasing the pixel work with higher levels of AA however quickly eliminates that bottleneck. In this game I find that 8xS delivers slightly better quality than SLI 8x. As well as slightly better performance. The horizontal edges seem to be slightly better anti aliased. 16xS verses SLI 16x is a different story. While I found both modes to be relatively unplayable. They delivered equivalent quality and the SLI16x mode seemed to scale better due to requiring less framebuffer space. 8xSAA seemed to offer the best compromise of performance quality. In this case it offered the same performance as 4xAA on a single or dual graphic card. There was no reason not to turn it on. Keep in mind that these performance results were run at high settings and actual in game performance will be more scalable at a loss in quality.


[b][center]Max Payne 2 [/b][/center]

[b] Max Payne 2[/b]: Max Payne 2 is a fairly older game by today's standing. It was a popular title in the days of the Geforce FX cards before SLI was available.. It proves to be very CPU limited on modern systems including SLI.

[b]4xAA[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/MP2/4xaa.png"]http://www.3declipse.com//images/stories/C...ou/MP2/4xaa.png[/url]

[b]8xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/MP2/8xs.png"]http://www.3declipse.com//images/stories/C...you/MP2/8xs.png[/url]

[b]SLI 8x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/MP2/sli8x.png"]http://www.3declipse.com//images/stories/C...u/MP2/sli8x.png[/url]

[b]16xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/MP2/16xs.png"]http://www.3declipse.com//images/stories/C...ou/MP2/16xs.png[/url]

[b] SLI 16x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/MP2/sli16x.png"]http://www.3declipse.com//images/stories/C.../MP2/sli16x.png[/url]

[b]Note[/b]: The 4x shot is not identical with the rest. But considering how little quality differences there were I did not see this as an earthshaking problem.

[center][img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/MP2/mp2graph.png[/img][/center]


[b] Performance Thoughts[/b]: Well I think the graph pretty much speaks for itself. In the case of this configuration. There is absolutely no reason not to run this game in absolute full quality at either 16xS or SLI 16x. However unfortunately the quality improvements are minimal from an edge aliasing perspective due the relatively low polygon count of Max Payne 2. The switch from 4x to 8x modes makes the largest difference.

[b][center]Battlefield 2 [/b][/center]

[b] Battlefield 2[/b]: Is EA's latest Battlefield game. It features a pretty good mix of shaders and high polygon counts. The game is much like Everquest 2 and features a good mix of CPU and GPU bottlenecks.

[b]4xAA[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/Battlefield2/4xaa.jpg"]http://www.3declipse.com//images/stories/C...field2/4xaa.jpg[/url]

[b]8xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/Battlefield2/8xs.jpg"]http://www.3declipse.com//images/stories/C...efield2/8xs.jpg[/url]

[b]SLI 8x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/Battlefield2/sli8x.jpg"]http://www.3declipse.com//images/stories/C...ield2/sli8x.jpg[/url]

[b]16xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/Battlefield2/16xs.jpg"]http://www.3declipse.com//images/stories/C...field2/16xs.jpg[/url]

[b] SLI 16x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/Battlefield2/sli16x.jpg"]http://www.3declipse.com//images/stories/C...eld2/sli16x.jpg[/url]

[b]Note:[/b] Due to a client error I was forced to use high quality JPEGs instead of PNG for the rest of my investigation. The JPEG are very high quality and shouldnt diminish quality in a negative way to make these comparisons less useful.

[center][img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/b2perf.png[/img][/center]

[b] Performance Thoughts:[/b] Even in 4xAA mode this game does not prove to be completely CPU limited. Enabling SLI produces even a small boost to performance at the lower settings. When comparing SLI 8x to 8xS once again I find myself preferring
8xS. Due to its supersampling positions it just filters the barb wired fence better than SLI 8x. 8xS also scales extremely well providing very playable framerates. When taking these considerations into account 8xS offers the best from a quality and performance perspective. However it should be noted the performance of SLI 8x is fairly efficient compared to a single card running 4xAA. 16xS and SLI 16x dont offer much difference in quality. However performance between the two differs a great deal. Due to 16xS massive framebuffer requirements it has a very hard time coping and keeping playable framerates. SLI 16x doesnt have this problem and is quite efficient when you consider its only 2 FPS slower than a single card running 8xS. SLI 16x was borderline playable with minimum framerates hitting 27 FPS on this map.
Performance and Quality




Performance: So what of Performance and Quality? Now that we have gone over the AA settings available to us we'll now get to see them in action. The next section of the investigation covers performance and quality of these AA settings through 5 well known games. All games were run in High Quality mode with anisotropic filtering set to 16x. All my benches are done in game via fraps.





Everquest 2






Everquest 2: Everquest 2 is a fairly new MMORPG. It is well known for being a very performance taxing application. It can feature a moderate amount of CPU and GPU limitation depending on your setup. SLI Configurations are often quickly limited by the CPU in this game.



Quality:



4xAA



http://www.3declipse.com//images/stories/C...ou/EQ2/4xaa.png



8xS



http://www.3declipse.com//images/stories/C...you/EQ2/8xs.png



SLI 8x



http://www.3declipse.com//images/stories/C...u/EQ2/sli8x.png



16xS



http://www.3declipse.com//images/stories/C...ou/EQ2/16xs.png



SLI 16x



http://www.3declipse.com//images/stories/C.../EQ2/sli16x.png



Note: These shots are not 100% identical due the weather pattern changes in MMORPGs, However still effectively demonstrate the quality differences.



Image





Performance thoughts: Clearly Everquest 2 is limited by the CPU to a good degree in this map. Increasing the pixel work with higher levels of AA however quickly eliminates that bottleneck. In this game I find that 8xS delivers slightly better quality than SLI 8x. As well as slightly better performance. The horizontal edges seem to be slightly better anti aliased. 16xS verses SLI 16x is a different story. While I found both modes to be relatively unplayable. They delivered equivalent quality and the SLI16x mode seemed to scale better due to requiring less framebuffer space. 8xSAA seemed to offer the best compromise of performance quality. In this case it offered the same performance as 4xAA on a single or dual graphic card. There was no reason not to turn it on. Keep in mind that these performance results were run at high settings and actual in game performance will be more scalable at a loss in quality.





Max Payne 2




Max Payne 2: Max Payne 2 is a fairly older game by today's standing. It was a popular title in the days of the Geforce FX cards before SLI was available.. It proves to be very CPU limited on modern systems including SLI.



4xAA



http://www.3declipse.com//images/stories/C...ou/MP2/4xaa.png



8xS



http://www.3declipse.com//images/stories/C...you/MP2/8xs.png



SLI 8x



http://www.3declipse.com//images/stories/C...u/MP2/sli8x.png



16xS



http://www.3declipse.com//images/stories/C...ou/MP2/16xs.png



SLI 16x



http://www.3declipse.com//images/stories/C.../MP2/sli16x.png



Note: The 4x shot is not identical with the rest. But considering how little quality differences there were I did not see this as an earthshaking problem.



Image






Performance Thoughts: Well I think the graph pretty much speaks for itself. In the case of this configuration. There is absolutely no reason not to run this game in absolute full quality at either 16xS or SLI 16x. However unfortunately the quality improvements are minimal from an edge aliasing perspective due the relatively low polygon count of Max Payne 2. The switch from 4x to 8x modes makes the largest difference.



Battlefield 2




Battlefield 2: Is EA's latest Battlefield game. It features a pretty good mix of shaders and high polygon counts. The game is much like Everquest 2 and features a good mix of CPU and GPU bottlenecks.



4xAA



http://www.3declipse.com//images/stories/C...field2/4xaa.jpg



8xS



http://www.3declipse.com//images/stories/C...efield2/8xs.jpg



SLI 8x



http://www.3declipse.com//images/stories/C...ield2/sli8x.jpg



16xS



http://www.3declipse.com//images/stories/C...field2/16xs.jpg



SLI 16x



http://www.3declipse.com//images/stories/C...eld2/sli16x.jpg



Note: Due to a client error I was forced to use high quality JPEGs instead of PNG for the rest of my investigation. The JPEG are very high quality and shouldnt diminish quality in a negative way to make these comparisons less useful.



Image




Performance Thoughts: Even in 4xAA mode this game does not prove to be completely CPU limited. Enabling SLI produces even a small boost to performance at the lower settings. When comparing SLI 8x to 8xS once again I find myself preferring

8xS. Due to its supersampling positions it just filters the barb wired fence better than SLI 8x. 8xS also scales extremely well providing very playable framerates. When taking these considerations into account 8xS offers the best from a quality and performance perspective. However it should be noted the performance of SLI 8x is fairly efficient compared to a single card running 4xAA. 16xS and SLI 16x dont offer much difference in quality. However performance between the two differs a great deal. Due to 16xS massive framebuffer requirements it has a very hard time coping and keeping playable framerates. SLI 16x doesnt have this problem and is quite efficient when you consider its only 2 FPS slower than a single card running 8xS. SLI 16x was borderline playable with minimum framerates hitting 27 FPS on this map.

#2
Posted 09/08/2006 03:30 AM   
[b][center]Half Life 2 [/b][/center]

[b] Half Life 2[/b]: If you dont know the Half Life 2 game I assume you've been living under a rock. ;) With the exception of the new episodes and lost coast this title has grown quite CPU limited on modern hardware. Paticularly SLI setups.

[b] Quality:[/b]

[b]4xAA[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/HL2/4xaa.jpg"]http://www.3declipse.com//images/stories/C...ou/HL2/4xaa.jpg[/url]

[b]8xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/HL2/8xsaa.jpg"]http://www.3declipse.com//images/stories/C...u/HL2/8xsaa.jpg[/url]

[b]SLI 8x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/HL2/sli8x.jpg"]http://www.3declipse.com//images/stories/C...u/HL2/sli8x.jpg[/url]

[b]16xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/HL2/16xsaa.jpg"]http://www.3declipse.com//images/stories/C.../HL2/16xsaa.jpg[/url]

[b]SLI 16x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/HL2/sli16x.jpg"]http://www.3declipse.com//images/stories/C.../HL2/sli16x.jpg[/url]

[center][img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/HL2/hl2aa.png[/img][/center]

[b] Performance Thoughts[/b]: This game is largely CPU limited at this resolution. 4xAA mode is actually slightly slower in SLI configuration due to this fact. 8xS and SLI 8x offer very similar quality in this game. SLI 8x rotated grid supersampling effect helps it do better on vertical speculiar aliasing on the lockers. However 8xS tends to offer better quality on the chain link fence. Performance proves nearly identical between the two other than SLI8x showing slightly less CPU overhead. In the end it will come down to user preference. 16xS and SLI16x once again produce virtually identical image output. Both significantly improving the quality of the scene. Both modes remain playable while SLI 16x is once again more efficient only losing 1 FPS to 8xS on a single card. At this resolution there's really no reason not to play in either 16xS or SLI 16x modes dependent on user preference.

[b][center]Serious Sam 2 [/b][/center]

[b]Serious Sam 2[/b]: Serious Sam 2 is another title that offers a good level of GPU and CPU bottlenecks. Its performance charactoristics are very similar too that of Battlefield 2.

[b] Quality:[/b]

[b]4xAA[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/SS2/4xaa.jpg"]http://www.3declipse.com//images/stories/C...ou/SS2/4xaa.jpg[/url]

[b]8xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/SS2/8xs.jpg"]http://www.3declipse.com//images/stories/C...you/SS2/8xs.jpg[/url]

[b]SLI 8x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/SS2/sli8x.jpg"]http://www.3declipse.com//images/stories/C...u/SS2/sli8x.jpg[/url]

[b]16xS[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/SS2/16xs.jpg"]http://www.3declipse.com//images/stories/C...ou/SS2/16xs.jpg[/url]

[b]SLI 16x[/b]

[url="http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/SS2/sli16x.jpg"]http://www.3declipse.com//images/stories/C.../SS2/sli16x.jpg[/url]

[center]
[img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/SS2/ss2aa.png[/img]
[/center]

[b]Performance Thoughts:[/b] Once again we see that SLI provides a small boost at 4xAA but quickly runs into a CPU bottleneck. This is the game that 8xS surprised me due its rather poor showing. In the case of this title the framebuffer requirements exceeded the cards onboard capacity and forced swapping into the system. SLI 8x due to the G71's more efficient SLI AA engine and lower framebuffer consumption really has a chance to spread its wings only being 4 FPS behind 4x AA on a single card. Overall the quality differences between the two modes is minimal with 8xS offering a slight edge in quality. However with the performance so far in SLI8x favor I'd have to vote in favor of SLI 8x mode. 16xS does paticularly bad due to its excessive framebuffer requirements. SLI 16x once again showing strong efficiency only losing 1 FPS to 8xS on a single GPU.

[center][b]Conclusion[/b][/center]

1) [b]Scaling:[/b] Scaling is going to be dependent on application. Some applications are more limited by pixel fillrate than others. Using modes such as 8xS and 16xS can dramatically increase the pixel fillrate requirement. Which will increase quality significantly and not affect performance much on CPU limited titles.

2)[b] 8xS or SLI 8x[/b]: This question is generally easily answered. 8xS tends to be the unsung hero of SLI configurations. Generally offering better quality and performance than SLI 8x. However this mode can be limited by its framebuffer consumption in comparison to SLI 8x as seen in Serious Sam 2. Generally I find that 8xS is the definate sweet spot for SLI configuration running this resolution. While SLI 8x is definately a great fallback for compatibility and games with high texture requirements and could possibly prove to be a faster solution as titles become increasingly sensitive to the amount of video ram. As noted in Serious Sam 2.


3) [b]16xS or SLI 16x[/b]: Due to 16xS massive framebuffer consumption and the relatively minor quality differences it is difficult to reccomend it over SLI 16x. Also add to the fact that 16xS is not a supported mode by Nvidia. Most of the time SLI 16x proved to be extremely efficient relative to the 8xS mode on a single card. Offering performance that is usually 1-2 FPS slower. Another thing to note about the 16xS mode. Often its framebuffer usage was so far and beyond the capacity of the GPU it would introduce stuttering in certain titles. ((Battlefield 2, Everquest 2))


[b] Overall Thoughts[/b]: Theres no definate answer for performance scaling. This is a merely guide to help people understand how to get the best from their hardware. Some might prefer to increase the resolution and others might prefer higher quality AA and are limited by their monitors or other factors. Since SLI's introduction users now have a multitude of options available to them and it is strongly urged that users experiment and find the best settings for their system.
Half Life 2




Half Life 2: If you dont know the Half Life 2 game I assume you've been living under a rock. ;) With the exception of the new episodes and lost coast this title has grown quite CPU limited on modern hardware. Paticularly SLI setups.



Quality:



4xAA



http://www.3declipse.com//images/stories/C...ou/HL2/4xaa.jpg



8xS



http://www.3declipse.com//images/stories/C...u/HL2/8xsaa.jpg



SLI 8x



http://www.3declipse.com//images/stories/C...u/HL2/sli8x.jpg



16xS



http://www.3declipse.com//images/stories/C.../HL2/16xsaa.jpg



SLI 16x



http://www.3declipse.com//images/stories/C.../HL2/sli16x.jpg



Image




Performance Thoughts: This game is largely CPU limited at this resolution. 4xAA mode is actually slightly slower in SLI configuration due to this fact. 8xS and SLI 8x offer very similar quality in this game. SLI 8x rotated grid supersampling effect helps it do better on vertical speculiar aliasing on the lockers. However 8xS tends to offer better quality on the chain link fence. Performance proves nearly identical between the two other than SLI8x showing slightly less CPU overhead. In the end it will come down to user preference. 16xS and SLI16x once again produce virtually identical image output. Both significantly improving the quality of the scene. Both modes remain playable while SLI 16x is once again more efficient only losing 1 FPS to 8xS on a single card. At this resolution there's really no reason not to play in either 16xS or SLI 16x modes dependent on user preference.



Serious Sam 2




Serious Sam 2: Serious Sam 2 is another title that offers a good level of GPU and CPU bottlenecks. Its performance charactoristics are very similar too that of Battlefield 2.



Quality:



4xAA



http://www.3declipse.com//images/stories/C...ou/SS2/4xaa.jpg



8xS



http://www.3declipse.com//images/stories/C...you/SS2/8xs.jpg



SLI 8x



http://www.3declipse.com//images/stories/C...u/SS2/sli8x.jpg



16xS



http://www.3declipse.com//images/stories/C...ou/SS2/16xs.jpg



SLI 16x



http://www.3declipse.com//images/stories/C.../SS2/sli16x.jpg





Image





Performance Thoughts: Once again we see that SLI provides a small boost at 4xAA but quickly runs into a CPU bottleneck. This is the game that 8xS surprised me due its rather poor showing. In the case of this title the framebuffer requirements exceeded the cards onboard capacity and forced swapping into the system. SLI 8x due to the G71's more efficient SLI AA engine and lower framebuffer consumption really has a chance to spread its wings only being 4 FPS behind 4x AA on a single card. Overall the quality differences between the two modes is minimal with 8xS offering a slight edge in quality. However with the performance so far in SLI8x favor I'd have to vote in favor of SLI 8x mode. 16xS does paticularly bad due to its excessive framebuffer requirements. SLI 16x once again showing strong efficiency only losing 1 FPS to 8xS on a single GPU.



Conclusion




1) Scaling: Scaling is going to be dependent on application. Some applications are more limited by pixel fillrate than others. Using modes such as 8xS and 16xS can dramatically increase the pixel fillrate requirement. Which will increase quality significantly and not affect performance much on CPU limited titles.



2) 8xS or SLI 8x: This question is generally easily answered. 8xS tends to be the unsung hero of SLI configurations. Generally offering better quality and performance than SLI 8x. However this mode can be limited by its framebuffer consumption in comparison to SLI 8x as seen in Serious Sam 2. Generally I find that 8xS is the definate sweet spot for SLI configuration running this resolution. While SLI 8x is definately a great fallback for compatibility and games with high texture requirements and could possibly prove to be a faster solution as titles become increasingly sensitive to the amount of video ram. As noted in Serious Sam 2.





3) 16xS or SLI 16x: Due to 16xS massive framebuffer consumption and the relatively minor quality differences it is difficult to reccomend it over SLI 16x. Also add to the fact that 16xS is not a supported mode by Nvidia. Most of the time SLI 16x proved to be extremely efficient relative to the 8xS mode on a single card. Offering performance that is usually 1-2 FPS slower. Another thing to note about the 16xS mode. Often its framebuffer usage was so far and beyond the capacity of the GPU it would introduce stuttering in certain titles. ((Battlefield 2, Everquest 2))





Overall Thoughts: Theres no definate answer for performance scaling. This is a merely guide to help people understand how to get the best from their hardware. Some might prefer to increase the resolution and others might prefer higher quality AA and are limited by their monitors or other factors. Since SLI's introduction users now have a multitude of options available to them and it is strongly urged that users experiment and find the best settings for their system.

#3
Posted 09/08/2006 03:31 AM   
Feel free to discuss or add any thoughts to this investigation :)

Chris
Feel free to discuss or add any thoughts to this investigation :)



Chris

#4
Posted 09/08/2006 03:55 AM   
Just wanted to add. Newer G71/G73 ((Geforce 7900/7600))hardware performs the SLIAA engine in hardware while the G70 and Nv4x ((Geforce 7800/Geforce 6800/Geforce 6600)) perform the process through the PCIE bus. Its something people will want to consider when they read this. As the G71 hardware can do it alot more efficiently.

[img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/g71versesg70sliaa.png[/img]
Just wanted to add. Newer G71/G73 ((Geforce 7900/7600))hardware performs the SLIAA engine in hardware while the G70 and Nv4x ((Geforce 7800/Geforce 6800/Geforce 6600)) perform the process through the PCIE bus. Its something people will want to consider when they read this. As the G71 hardware can do it alot more efficiently.



Image

#5
Posted 09/08/2006 10:20 AM   
ChrisRay

Very good investigation and I appreciate all the work you have put into this.

How can I relate these various AA modes to my 7950GX2 ?

Whilst a single multi-GPU card it has some of the features of a traditional SLI setup
In my AA option, for example, I have 8XS and 8X. How do they compare to those same modes as outlined in your article, bearing in mind you have SLI 8X where I only have 8X

cheers
ChrisRay



Very good investigation and I appreciate all the work you have put into this.



How can I relate these various AA modes to my 7950GX2 ?



Whilst a single multi-GPU card it has some of the features of a traditional SLI setup

In my AA option, for example, I have 8XS and 8X. How do they compare to those same modes as outlined in your article, bearing in mind you have SLI 8X where I only have 8X



cheers

#6
Posted 09/09/2006 09:02 AM   
[quote name='bagman' date='Sep 9 2006, 01:02 AM']ChrisRay

Very good investigation and I appreciate all the work you have put into this.

How can I relate these various AA modes to my 7950GX2 ?

Whilst a single multi-GPU card it has some of the features of a traditional SLI setup
In my AA option, for example, I have 8XS and 8X. How do they compare to those same modes as outlined in your article, bearing in mind you have SLI 8X where I only have 8X

cheers
[right][post="112636"]<{POST_SNAPBACK}>[/post][/right][/quote]


Good question about the 8x mode. That one is a slight mystery to me. ((I am guessing its a variation of SLI 8x)) I'll see what I can find out. In general for now I'd look over the 8xS numbers and use them as a basis because they will function identically across the two setups.. When Multi GPU rendering is disabled. What happens to the other 8x mode? I am pretty sure that 7950 GX2 does not offer the same level of AA alternatives as SLI. But I'll see about getting the information you requested.

Chris
[quote name='bagman' date='Sep 9 2006, 01:02 AM']ChrisRay



Very good investigation and I appreciate all the work you have put into this.



How can I relate these various AA modes to my 7950GX2 ?



Whilst a single multi-GPU card it has some of the features of a traditional SLI setup

In my AA option, for example, I have 8XS and 8X. How do they compare to those same modes as outlined in your article, bearing in mind you have SLI 8X where I only have 8X



cheers

[post="112636"]<{POST_SNAPBACK}>[/post]






Good question about the 8x mode. That one is a slight mystery to me. ((I am guessing its a variation of SLI 8x)) I'll see what I can find out. In general for now I'd look over the 8xS numbers and use them as a basis because they will function identically across the two setups.. When Multi GPU rendering is disabled. What happens to the other 8x mode? I am pretty sure that 7950 GX2 does not offer the same level of AA alternatives as SLI. But I'll see about getting the information you requested.



Chris

#7
Posted 09/09/2006 09:49 AM   
[quote name='ChrisRay' date='Sep 9 2006, 07:49 PM']Good question about the 8x mode.  That one is a slight mystery to me. ((I am guessing its a variation of SLI 8x)) I'll see what I can find out. In general for now I'd look over the 8xS numbers and use them as a basis because they will function identically across the two setups.. When Multi GPU rendering is disabled. What happens to the other 8x mode?  I am pretty sure that 7950 GX2 does not offer the same level of AA alternatives as SLI. But I'll see about getting the information you requested.

Chris
[right][post="112644"]<{POST_SNAPBACK}>[/post][/right][/quote]

Thanks so much.
I am currently running 91.31 as I find them compatible with a lot of older games and in particular the MOHAA series. Yes I appreciate that is an old series, but sometimes it's good to play them again.
I found that with any version over 91.31 the game would crash to desktop just past the loading screen. Very strange.

Under "Manage 3D Settings" I have the following enabled:"
Set multi-GPU configuration: multi-GPU mode enabled

Under Gloabl Settings I have everything at default except:
Hardware Acceleration: Single Display Performance mode ( only 1 monitor)
Multi-GPU Performnace mode: Single-GPU rendering

Whatever details you can find out regarding the 8X modes would be greatly appreciated.

cheers
[quote name='ChrisRay' date='Sep 9 2006, 07:49 PM']Good question about the 8x mode.  That one is a slight mystery to me. ((I am guessing its a variation of SLI 8x)) I'll see what I can find out. In general for now I'd look over the 8xS numbers and use them as a basis because they will function identically across the two setups.. When Multi GPU rendering is disabled. What happens to the other 8x mode?  I am pretty sure that 7950 GX2 does not offer the same level of AA alternatives as SLI. But I'll see about getting the information you requested.



Chris

[post="112644"]<{POST_SNAPBACK}>[/post]




Thanks so much.

I am currently running 91.31 as I find them compatible with a lot of older games and in particular the MOHAA series. Yes I appreciate that is an old series, but sometimes it's good to play them again.

I found that with any version over 91.31 the game would crash to desktop just past the loading screen. Very strange.



Under "Manage 3D Settings" I have the following enabled:"

Set multi-GPU configuration: multi-GPU mode enabled



Under Gloabl Settings I have everything at default except:

Hardware Acceleration: Single Display Performance mode ( only 1 monitor)

Multi-GPU Performnace mode: Single-GPU rendering



Whatever details you can find out regarding the 8X modes would be greatly appreciated.



cheers

#8
Posted 09/09/2006 12:46 PM   
Hey Bagman, I havent forgotten. Just waiting to get some data from Brian S which may answer your question.

I delved a little deeper the G71 efficiency with the SLI link connector running SLIAA. Removing the bridge definately gives the G71/G73 cores a performance hit more in line with older hardware.

[img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/splintersliaa.png[/img]
Hey Bagman, I havent forgotten. Just waiting to get some data from Brian S which may answer your question.



I delved a little deeper the G71 efficiency with the SLI link connector running SLIAA. Removing the bridge definately gives the G71/G73 cores a performance hit more in line with older hardware.



Image

#9
Posted 09/10/2006 09:06 AM   
[quote name='ChrisRay' date='Sep 10 2006, 07:06 PM']Hey Bagman, I havent forgotten. Just waiting to get some data from Brian S which may answer your question.

I delved a little deeper the G71 efficiency with the SLI link connector running SLIAA. Removing the bridge definately gives the G71/G73 cores a performance hit more in line with older hardware.

[img]http://www.3declipse.com//images/stories/ChrisRay/SLIforyou/splintersliaa.png[/img]
[right][post="112843"]<{POST_SNAPBACK}>[/post][/right][/quote]

Hi there ChrisRay
Thanks again for replying
I must confess to being a little confused by that last post. I'm wondering if you would mind explaining how that relates to my 7950GX2 please ?

On a slightly related matter. With the 91.47 drivers I am having trouble running the old Medal of Honor series. The game will load all the way up to where a save game is about to load, and then crashes to desktop with the message "WARNING: Medal of Honor requires a video card with multitexturing capability "
Not sure if you can help with that, but perhaps you could pass onto the appropriate people who can see if it is a driver issue or related to the 7950GX2.
The game worked fine with my old 7800GTX

cheers and many thanks again
Bagman
[quote name='ChrisRay' date='Sep 10 2006, 07:06 PM']Hey Bagman, I havent forgotten. Just waiting to get some data from Brian S which may answer your question.



I delved a little deeper the G71 efficiency with the SLI link connector running SLIAA. Removing the bridge definately gives the G71/G73 cores a performance hit more in line with older hardware.



Image

[post="112843"]<{POST_SNAPBACK}>[/post]




Hi there ChrisRay

Thanks again for replying

I must confess to being a little confused by that last post. I'm wondering if you would mind explaining how that relates to my 7950GX2 please ?



On a slightly related matter. With the 91.47 drivers I am having trouble running the old Medal of Honor series. The game will load all the way up to where a save game is about to load, and then crashes to desktop with the message "WARNING: Medal of Honor requires a video card with multitexturing capability "

Not sure if you can help with that, but perhaps you could pass onto the appropriate people who can see if it is a driver issue or related to the 7950GX2.

The game worked fine with my old 7800GTX



cheers and many thanks again

Bagman

#10
Posted 09/10/2006 10:18 AM   
Oh it doesnt relate to your last post. I am getting the information from Brian_S and going to wait till I have some solid information on the 7950 GX2 SLI modes. Does the game work with other drivers?

My graph was related to the current investigation and I had just moved onto discussing it with my next paragraph. Sorry about the confusion :)
Oh it doesnt relate to your last post. I am getting the information from Brian_S and going to wait till I have some solid information on the 7950 GX2 SLI modes. Does the game work with other drivers?



My graph was related to the current investigation and I had just moved onto discussing it with my next paragraph. Sorry about the confusion :)

#11
Posted 09/10/2006 11:53 AM   
[quote name='ChrisRay' date='Sep 10 2006, 09:53 PM']Oh it doesnt relate to your last post. I am getting the information from Brian_S and going to wait till I have some solid information on the 7950 GX2 SLI modes.  Does the game work with other drivers?

My graph was related to the current investigation and I had just moved onto discussing it with my next paragraph. Sorry about the confusion :)
[right][post="112855"]<{POST_SNAPBACK}>[/post][/right][/quote]

Thanks again for the work you are doing on this investigation.
The outcomes make it much easier for relative novices like myself to get a better understanding on how the complex world of graphics work.

As to MOHAA, the game was working with the 91.31's then the other day it started crashing with them. Same message re " video card with multitexturing capability ".
I uninstalled the game completely plus the 91.31's. That included registry entries for the game and the drivers. Installed the game and 91.47 drivers, plus any patch for MOHAA. Now MOHAA works, but the expansion packs
( Breakthrough/Spearhead) dont even get past the initial loading screen before crashing to desktop. No "multitexturing capability " message, just crash to desktop.

I had this issue once before when running my 7800GTX and 84.43 drivers. I found that provided there was only the one game profile ( i.e. MOH Allied Assault) the expansion packs played without any issues.

I've tried deleting the game profiles from the nvapp.xml file in Windows\System32 for the 91.47 and 91.31 drivers but makes no difference.

cheers and many thanks again for your assistance. Very generous of you and your time

Bagman
[quote name='ChrisRay' date='Sep 10 2006, 09:53 PM']Oh it doesnt relate to your last post. I am getting the information from Brian_S and going to wait till I have some solid information on the 7950 GX2 SLI modes.  Does the game work with other drivers?



My graph was related to the current investigation and I had just moved onto discussing it with my next paragraph. Sorry about the confusion :)

[post="112855"]<{POST_SNAPBACK}>[/post]




Thanks again for the work you are doing on this investigation.

The outcomes make it much easier for relative novices like myself to get a better understanding on how the complex world of graphics work.



As to MOHAA, the game was working with the 91.31's then the other day it started crashing with them. Same message re " video card with multitexturing capability ".

I uninstalled the game completely plus the 91.31's. That included registry entries for the game and the drivers. Installed the game and 91.47 drivers, plus any patch for MOHAA. Now MOHAA works, but the expansion packs

( Breakthrough/Spearhead) dont even get past the initial loading screen before crashing to desktop. No "multitexturing capability " message, just crash to desktop.



I had this issue once before when running my 7800GTX and 84.43 drivers. I found that provided there was only the one game profile ( i.e. MOH Allied Assault) the expansion packs played without any issues.



I've tried deleting the game profiles from the nvapp.xml file in Windows\System32 for the 91.47 and 91.31 drivers but makes no difference.



cheers and many thanks again for your assistance. Very generous of you and your time



Bagman

#12
Posted 09/10/2006 09:53 PM   
Hi,

I too have this problem with mohaa, using 91.32 drivers for my Leadtek GeForce 7600GT 256mb (AGP) this starting happening as soon as microsoft updated to the August DirectX. I cant play it and just get the message about needing a graphics card with multitexturing capability.

I dont use SLi and it all worked fine with 91.32 before the august update of directx.

Any ideas? I had this before and the only way for me to solve it was to reformat and not install the august directx, obviously I dont want to reformat again :(
Hi,



I too have this problem with mohaa, using 91.32 drivers for my Leadtek GeForce 7600GT 256mb (AGP) this starting happening as soon as microsoft updated to the August DirectX. I cant play it and just get the message about needing a graphics card with multitexturing capability.



I dont use SLi and it all worked fine with 91.32 before the august update of directx.



Any ideas? I had this before and the only way for me to solve it was to reformat and not install the august directx, obviously I dont want to reformat again :(

#13
Posted 09/20/2006 05:14 PM   
[quote name='cool96' date='Sep 21 2006, 03:14 AM']Hi,

I too have this problem with mohaa, using 91.32 drivers for my Leadtek GeForce 7600GT 256mb (AGP) this starting happening as soon as microsoft updated to the August DirectX. I cant play it and just get the message about needing a graphics card with multitexturing capability.

I dont use SLi and it all worked fine with 91.32 before the august update of directx.

Any ideas? I had this before and the only way for me to solve it was to reformat and not install the august directx, obviously I dont want to reformat again :(
[right][post="115020"]<{POST_SNAPBACK}>[/post][/right][/quote]

From my reading of various forums around the web, this is a very common problem that quite a number of us are experiencing.
I have contacted both EA support and nVidia for some suggestions, but none have proved successful.
EA basically suggested un-installing the game and trying installing on a different user ID in XP Pro. That didn't work and neither did installing on a seperate hard drive.
nVidia suggested trying 91.33 which did nothing. The game used to work with 91.31's but now the game suffers the same problem with them
I'm hoping that nVidia are trying to re-produce this issue in their testing system and see if a driver up-date might help.

cheers
[quote name='cool96' date='Sep 21 2006, 03:14 AM']Hi,



I too have this problem with mohaa, using 91.32 drivers for my Leadtek GeForce 7600GT 256mb (AGP) this starting happening as soon as microsoft updated to the August DirectX. I cant play it and just get the message about needing a graphics card with multitexturing capability.



I dont use SLi and it all worked fine with 91.32 before the august update of directx.



Any ideas? I had this before and the only way for me to solve it was to reformat and not install the august directx, obviously I dont want to reformat again :(

[post="115020"]<{POST_SNAPBACK}>[/post]




From my reading of various forums around the web, this is a very common problem that quite a number of us are experiencing.

I have contacted both EA support and nVidia for some suggestions, but none have proved successful.

EA basically suggested un-installing the game and trying installing on a different user ID in XP Pro. That didn't work and neither did installing on a seperate hard drive.

nVidia suggested trying 91.33 which did nothing. The game used to work with 91.31's but now the game suffers the same problem with them

I'm hoping that nVidia are trying to re-produce this issue in their testing system and see if a driver up-date might help.



cheers

#14
Posted 09/20/2006 10:23 PM   
Wouldn't these tests be better comparisons at a higher resolution? Say 1600 x 1200?

Rich
Wouldn't these tests be better comparisons at a higher resolution? Say 1600 x 1200?



Rich

#15
Posted 11/20/2006 04:37 PM   
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