I have/had Win8 in my main system, lately I was noticing that I was dropping one of my cards in SLI. Tried all the swapping around,slot for slot, thought I had it last night after running multiple of Unigine. Went on and played some freeze tag and card drops out. Had already tried swapping drivers to older and was just beginning to start checking for a defective card when i thought screw it. Put my 120SSD back in and reformatted with Win7..hmm..both cards running, last Unigine in Win8 netted 1654...now 2635. Win 8 may just suck more than I thought...I may boot back over to my HD that has Win 8 on it to play more and troubleshot..but ..yeah..might not be worth it...and I bought 3 licenses for it too.So just a heads up if anybody else starts noticing funky crap happenning.