Severe bottleneck on 2 1080Ti's- Please Help

[Sgt Platypus]

I was so damn disappointed to find that my new EVGA SC 1080Ti's in SLI were barely an upgrade over my old SLI Titan X's (Maxwell). Im seeing maybe a 5-10FPS increase in gaming generally. I play at 4K games like Fallout, Witcher, Ghost Recon, The Division.

If people are able to keep a constant 60FPS at 4K on Ultra settings with a single 1080Ti, then why cant I get close to that with 2?

Im unsure but I believe that my Mobo is doing x8/x8 on the GPUs but I could be wrong. Please tell me where my issue lies. Im ready to upgrade the CPU and Motherboard right now.

Specs-
i7 4790K 4.0GHz
Asus Sabertooth Mk. 2 Z97
(2) EVGA SC 1080Ti's SLI
16GB Ripjaws RAM
2TB Samsung Evo SSD
Coolmax PSU 1000W
NZXT H440 Case
Stock fans and cooling, nothing overclocked

 

[elbert]

Test your hardware with aida64 and furmark. If everythig is fine you should start from fresh windows install. You may first tho try uninstalling Nvidia drivers in control panel. Use DDU to remove all configs then reinstall fresh new video drivers.
http://www.guru3d.com/files-details/display-driver-uninstaller-download.html
https://www.aida64.com/
http://www.ozone3d.net/benchmarks/fur/