I was having some questions with a upgrade I am planning on. I have a M5A97 mobo with 2.0 x16 gpu slots and i was going to upgrade my Radeon 6970 with a Nvidia 660 ti which is 3.0 x16 compatible. Will the 660 ti work with the motherboard and if so is there a difference?
AMD Phenom II X6 3.3 GHz Processor
AMD Radeon 6970 HD
8 gigs of DDR3 ram
Asus M5A97 motherboard
Yes it will work because it's backward compatible so don't worry.
PCI-Express 3.0 almost have twice the bandwidth as 2.0, but the real question is does your bandwidth gets saturated otherwise you won't see any difference between the two. PCI-E 3.0 will shine more with a Crossfire or SLI setups because those require more bandwidth, but for a single card solution PCI-E 2.0 will have sufficient bandwidth in almost every scenarios so you shouldn't really see a difference, unless maybe you put a 690 or 7990 in your slot, lol.
But I would be curious to know why you are changing your card? In my book, a 6970 performs too close to a 660-Ti to be worth it (there might be a 10% difference between the two or something). I would suggest you wait at least 6 months for the new 8000-series or 700-series which should come out during the first quarter of 2013. Or if you really want to change now, at least get a 670 or a 7970 if you want to see some real improvement in performance...