Just an FYI as it seems getting more than 6 cards running in one system has been problematic for folks.

I'm now running (7) EVGA GTX 750Ti FTWs on an ASRock Fatil1ty Z87 Killer motherboard (Win7 x64). I had some problems getting normal risers to work (required jumping the vga presence pin), but USB risers have worked flawlessly without needing a jumper. Just make sure to disable the onboard video. If anyone wants more details, I'm happy to share.