The Nvidia (GDC 2015) Developers' Conference had an excellent presentation on SLI & stutter avoidance. The pdf of the presentation can be found at the following link: http://developer.download.nvidia.com/assets/events/GDC15/GEFORCE/SLI_GDC15.pdf Valuable reading. The first clear, recent explanation I have come across from Nvidia detailing the pros, cons, differences and possible solutions to the micro-stuttering inherent in SLI configurations. Regards, otta56
Cool, I'd love to see/hear the presentation as the slides don't give much detail. I can't tell if they're trying to develop a new way of doing things, trying to encourage devs to send games in for SLI profiling, if this has anything to do with DX12 (which apparently is supposed to make a big difference with SLI / Crossfire), etc. but thanks for the pdf. It's good to see SLI being strong and in-need possibly more than ever due to increasing pixel count thanks to 21:9 monitors (especially the 1440p ones), 4K, and 5K monitors being available, (not to mention 8K in the next few years), plus the move to higher refresh rates (100 - 144 Hz) which require equal value framerates to get the best out of, and 3D which takes around double the power for the advertised refresh rate due to an image for each eye (e.g. 90 Hz is actually 90 Hz per eye so in effect you need to pump out 180 fps to reach "90 fps").
Some short takeaways for end-users from the slides: 1. Set maximum pre-rendered frames to n+1 where n is the number of gpus present in the sli setup. For 2-way sli; 3 frames. 2. Use AFR2 rather than AFR 1 in all profiles unless there are image corruption issues. Scaling is better. 3. Set 'Vertical Sync Smooth AFR behavior' to on in the profile. The setting controls inter-frame dependencies to some extent. The rest of the info is more useful to game devs. The top bits of advice: 1. "Getting testing builds to NVIDIA early (Please ) for SLI profiling, identification issues, advice." 2. "QA SLI on 3-way configuration. Needs profile or AFR FriendlyD3D.exe to scale." Neither of these appear to have been done for any of the many rF2 builds.
A video of the GDC2015 conference talk 'NVIDIA SLI and Stutter Avoidance: A Recipe for Smooth Gaming and Perfect Scaling with Multiple GPUs' is now available at: http://www.gdcvault.com/play/1022388/ Regards
Here is a link to a more detailed analysis on the causes of stuttering from GDC China 2012 https://developer.nvidia.com/sites/default/files/akamai/gameworks/CN/Stuttering_Analysis_EN.pdf
