I recently upgraded my motherboard and cpu and now I'm going to to buy a new windows but I'm wondering if I should buy windows 7 or 8? What do you suggest for gaming? I have an amd fx 6300 and I heard somwhere that windows 8 takes more advantage of more cores!?
Win8 is technically better, but the user interface and backwards compatability sucks.
You can make Win8 look like Win7 for a $3 mod. I personally use Win8 because of the performance boost, but it doesn't let me play too many games that pre-date the Vista era.
I'd stick with Windows 7 for now to avoid running into problems with todays games, but further down the road the situation should eventually swing to 8's favor. The question is whether Windows 9 appears before that becomes a real factor through. ;)
There is a patch for Windows 7 that improves the threading for AMD bulldozer cores. But both that patch and Windows 8 itself doesn't make that much of a difference. If an older game acts up performance-wise you might want to look for information on how it well it can handle multiple cores to begin with, especially as six is an "odd" number that some games does not expect to exist.