Currently using an AMD 965BE running @ 3.89Ghz and an ATI 6950 2GB playing mostly WOW, but have played many other games and will sometimes get in on a great looking shooter for eye candy. My wife is willing to buy a new MB and i5 3570K for Christmas, and I was wondering if I would see much of a difference in FPS in WOW (large raids ect) or if I'd be a little bottle necked by the gpu. I game with a single monitor at 1080P. Thanks!
Install MSI Afterburner, Use its monitor to see your GPU usage. Play your games and watch it. If its at 99% on the more demanding games you have NO cpu bottleneck. If it is Struggling to hit 99% its most likely your cpu. From my experience the answer is Yes you will notice. Very much depends on what fps games though. BF3 for example would gain nicely