Ok. I was just about to unscrew the video card from the water block, remount stock heat sink, and take it back, when i thought: What the hell, won't hurt to check it one last time. Good thing i did, because now it's suddenly working perfectly again!
Why this is the case, is rather unclear to me, but my theory is that the new nVidia drivers may have solved it, but that's just a theory. Just thought i'd let you all know about this strange stuff.
Also, MFW it actually worked again:
http://files.sharenator.com/politica...264432-580.jpg