My speeds and GPU utilization on my 680 slower in 3 way sli vs. 2 way

Hi guys wondering if you can help out. I decided to get a third 680 and run 3 way sli as I have a 3D vision surround setup running at 5760 x 1080p, and adding 3D drops the frame rate in half. So I need a high end setup.

I've got a Rampage IV extreme Mobo, a 1200 watt OCZ PSU, a Intel 3930k OCed to 4.7gz, 3 680s EVGA, and I'm running it at PCI E 3.0.

With 2 cards running in SLI, I get very good utilization at around 90 - 99 for most games and FPS boost to match.

Adding the 3rd card, I noticed that Utilization is ALL OVER the place. Many times it's as low as 50 across all three cards. Some games it's in the 60 -70 range, but rarely does it get to the 90s.

I've tried many Nvidia drivers (including the latest ones) I've upgraded my mobo firmware, and pretty much did everything I could. Made sure the cards are in the right slots and used to hack for PCI 3.0.

I used both MSI afterburner and EVGA precision x to verify to low usage, and fraps to monitor FPS.

In many games I'm actually getting better performance from 2 way SLI vs. 3 way SLI.

In BF3, Inversion, and Sleeping dogs I get better performance with 2 way SLI and great scaling.

The only game that seems to benefit at all is Max payne 3 which saw improvement on only certain levels with a good boost in performance and utilization.

I weird thing I noticed with some games is that if for example I run Sleeping Dogs at high settings I get utilization between 50 - 60 on each card and 40fps. If I crank up the settings to extreme I get upto 90% utilization and still get 40fps. I then tried low settings and got around 40% utilization and 40 fps. Doesn't matter what settings I use I get a similar framerate. Really strange.

Does anyone have any advice or has anyone else come across this problem with horrible scaling across surround resolutions?

I'm thinking of just selling the 3rd card now and just running SLI, but I also didn't buy a top end rig for nothing and I'm really worried that It's something in my hardware causing this.

THanks guys.
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  1. Really sucks, as I'm actually someone who needs all these cards just to get a decent framerate.

    Whats the best way to test if it's a CPU issue? My CPU is crazy good, and I don't see how it can be a bottleneck.
  2. i have the same issue with gtx 680 sli on surround vision {2Ds frame rates drop and only at 75 - 80 % of usage. i this is due to sleeping dogs not supporting sli?????
  3. try border lands 2 it just had an update and it smokin with gtx sli 2d surround vision!!!
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