EDIT: Going to try to simplify the problem/information now that I've made a little bit of progress. There is still some funny behaviors around frame rates though.
VSYNC was culprit of the original issue which limiting FPS to 40 with huge input lag when running in SLI. Running a single card with the exact same settings it can go up to 60fps. Not sure why VSYNC affects SLI more than single card. GPU utilization was not maxxed out with VSYNC enabled. TV is 60hz so i'm not sure why VSYNC would limit it to 40hz with SLI.
Disabling VSYNC improved the performance but I still wanted to cap FPS at 60fps. To get around this, I turned off VSYNC on Nvidia Control Panel but enabled a FPS Limiter on Nvidia Inspector for 60hz. So far so good, it seems limited and doesn't have the input lag I had with VSYNC.
I did some more testing, I THINK SLI is working, though the results are a little strange so I am having a hard time understanding if this is expected or not.
I did some testing in FO4, exact same conditions between the two tests. Single Card gets as low as 35fps and topped out around 52fps. With SLI it is steady between 44-47fps. Basically with SLI I get better minimums but lower maximums. I am glad minimums are better but I would have expected improvements to maximums too.
This is on an older P67 motherboard, so I think they are running @ PCI-E 2.0 8x but I don't think that will impact performance too much.
Equipment
Motherboard - Asus P67 Sabertooth
CPU - i7 2600k @ 4.5ghz
RAM - Corsair 16GB 4x4GB @ 1600mhz
GPU - 2x 980 Ti w/ SLI (stock boost/clocks, not overclocked yet)
VSYNC was culprit of the original issue which limiting FPS to 40 with huge input lag when running in SLI. Running a single card with the exact same settings it can go up to 60fps. Not sure why VSYNC affects SLI more than single card. GPU utilization was not maxxed out with VSYNC enabled. TV is 60hz so i'm not sure why VSYNC would limit it to 40hz with SLI.
Disabling VSYNC improved the performance but I still wanted to cap FPS at 60fps. To get around this, I turned off VSYNC on Nvidia Control Panel but enabled a FPS Limiter on Nvidia Inspector for 60hz. So far so good, it seems limited and doesn't have the input lag I had with VSYNC.
I did some more testing, I THINK SLI is working, though the results are a little strange so I am having a hard time understanding if this is expected or not.
I did some testing in FO4, exact same conditions between the two tests. Single Card gets as low as 35fps and topped out around 52fps. With SLI it is steady between 44-47fps. Basically with SLI I get better minimums but lower maximums. I am glad minimums are better but I would have expected improvements to maximums too.
This is on an older P67 motherboard, so I think they are running @ PCI-E 2.0 8x but I don't think that will impact performance too much.
Equipment
Motherboard - Asus P67 Sabertooth
CPU - i7 2600k @ 4.5ghz
RAM - Corsair 16GB 4x4GB @ 1600mhz
GPU - 2x 980 Ti w/ SLI (stock boost/clocks, not overclocked yet)
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