Horrible performance with dual SLI on 2x EVGA 560 Ti (Ubuntu 12.10 + Cinnamon + 310.14)

Graphics / Linux Linux
#1

Hello,

I have recently upgraded my monitor from 1920x1080 to 2560x1600 and turns out a single 560 Ti is not really enough to run full screen games on it, so I bought another 560 Ti (exact same) hoping it would boost performance.

However when I turned on SLI (using sudo nvidia-xconfig --sli=on and started running games that normally ran at 30-50 FPS, now ran at 5-10 FPS.

I’m not sure what information to supply with this report, but I will gladly provide any such information.

#2

I’ve found that default SLI and AFR mode (I think they are the same) generally do not give good performance. I have much better luck with SFR mode (Split Frame Rendering) and do see a significant boost vs. a single card with this mode.

#3

I have the same results for the most part with 3 GTX 480’s.

#4

I have tried SFR (sudo nvidia-xconfig --sli=sfr) and while the performance decrease is gone, there is no performance increase - I get the same FPS I get without SLI.

Did I purchase a second card for nothing?

#5

Hi LiraNuna,

What games are you trying to run specifically? The only games with an SLi profile currently exposed on Linux are Doom 3, Quake 4 and ETQW through the __GL_DOOM3 environment variable as described there:

ftp://download.nvidia.com/XFree86/Linux-x86/310.19/README/sli.html

Thanks,

  • Pierre-Loup
#6

Can you please elaborate what SLi profile means? As a developer, I have read about SLi and the fact that it is passive (driver side work). I understand that GPU sync can be a bottleneck but clearly not for every use case. There is no SLi SDK anywhere where games need to be ‘SLi Enabled’ with or anything the like.

I am specifically running games (under WINE) such as World of Tanks, EVE Online and PlanetSide 2. They all run relatively well (50+ steady FPS) but when SLi is turned on I either don’t get any speed increase (SFR mode) or a massive performance drop (usually 40-50% of the original speed) on other modes.

In case there is doubt about WINE’s performance, I also ran the Unigine Heaven Benchmarks, which resulted the exact same performance characteristics.

I will be happy to supply any hardware, software or configuration that I have in order to help.