NVidia 296.10 SLI GPU Utilization Test Results
The graphs in the attached pdf file show GPU utilization for various AA & Transparency filtering combinations. It appears that 32xCSSA and 8xSS is the maximum combination two GTX580 cards with 3 GB of memory each can support at 60 FPS in Build 69. Any combination of Sparse Grid Super Sampling AA (SGSSAA) causes a significant loss in frame rates of anywhere from 25 - 50%. SLI does appear to be working well though with cpu utilization rates tracking closely for both cpus.
All settings in rF2 were at maximum except for shadows set at low. 25 AI cars and one lap of Spa per combination of settings. 8AA & 16 AF no HDR. HDR still does not work correctly with the center screen bleached white and the outer screens black. Textures in building windows, signs and billboards around the circuit still flicker. Some flickering of trees and roadside objects as well.
32xCSSA & 8xSS has the most fluid framerates at 60 fps for the first part of the circuit and 50-60 fps for the back half of of the circuit where there are more trees in the side panels. Aliasing is most visible on lines in the road and on the edge of armco barriers,
32xS & 2xSGSSAA has the worst frame rates at 35-40 fps on the front half of the circuit and 29-32 fps for the back half. There is no aliasing visible on road lines and armco with these settings.
Frame rates begin to stutter whenever the gpu utilization hits 99%.
Sparse Grid Super Sampling gives the best image quality with the least amount of aliasing but at the greatest frame rate performance cost.
Gpus are clocked at 832 MHz, memory 2100 MHz and shaders 1664 MHz. Screen resolution is 6028x1200.
Can you elaborate on the Stuttering please? Do you see the stuttering when racing spa witrh 20 AI. Take off is smooth as is first corner, but there onwards is a lagfest mess for me. I switch off back to single 580 and the world is smooth. During my lag, i never see the FPS drop at all. Would appreciate your feedback. Thanks.
Originally Posted by otta56
I use Spa with all settings at max except for shadows which are turned off. 25 Ai and multiview. Standard rF 2 NVidia profile, SLI and 6028X1200 resolution. Stuttering begins when exiting pits and continues to top of the first hill. Smooth framerates until the first set of buildings then more stuttering. Stuttering is mostly around curves with buildings and/or trees. The charts show that stuttering happens when gpus hit 100% utilization. Stuttering is two types, hesitation and large frame rate drops as well as 'rubber band effect' as if frame rendering stops momentarily and then resumes with a lage number of frames being rendered at once, always on the same sections of track. This seems to an SLI issue under AFR2 since it is minimal using SFR setting. SFR frame rates are 1/2 of AFR2 rates and the Gpus run 5-7 degrees hotter though. Both rF2 code and NVidia drivers need to be optimized before stuttering can be reduced. The stuttering is evident on all other tracks as well, always in the same places per track. Even GTX 580 3GB in SLI seem unable to produce smooth frame rates at high resolutions. My other SLI posts provide more results if you are interested. There is some improvement with 301.24 beta drivers using adaptive vsync setting, but rubber band effect is still pronounced on all tracks at maximum settings. Adaptive vsync may help reduce lag. Remember to turn off in game vsync setting when using adaptive vsync in 301.24 drivers so video card can handle frame rate limiting correctly.
Originally Posted by jonchard
Last edited by otta56; 04-16-12 at 02:02 AM.
Reason: Spelling corrections
That sounds like some of my issues!! I get triple screens this week and will see if its just as pronounced. Thanks for the feedback.
My experience performance wise at 5760*1080 WITH DUAL 580'S IS PRETTY AWFUL. It shows high FPS, but plays like its at 20-30 fps not the 70-80 it shows. Waiting for optimisations now. otta56, thanks for all the detail, you seem pretty clued into my problems.
You may want to try the profile settings in the attached file. They don't eliminate all of the problems, but frame rates are playable and the stuttering is minimized.
Keep in mind I am using 3 GB GTX580 cards, so the extra memory may make a difference. Also, turning off multiview will increase the frame rate by about 10 fps. You will have to change the in-game FOV to about 22-23, otherwise the side panels may look too distorted. If you are using 5760X1080 rather than 5760X1200, you may have to experiment a bit with the field of view setting. These results are valid for the NVidia 301.24 driver.