Low fps in most games all of a sudden

Hey guys, I built my own pc last year and it's ran games perfectly fine on max settings 1920x1080 until recently I've been struggling to play some higher end games and even lagging in f2p games. My system config consist of an unlock 6950 2gb amd sapphire gpu, a 955 amd phenom ii processor, 8gb ram, 750 watt psu, and I'm pretty sure my motherboard is fine.

Games like Planetside 2 on high settings with 1920x1080 resolution I'm only able to get 18-25 fps outdoors. I tried the Crysis 3 beta and I struggled to get anything above 20 fps in that. In Dota 2 I'm getting as low as 45 fps to 60 fps. The weird thing is even if I lower the settings on Planetside 2 and Crysis the fps barely changes maybe 1-3 fps faster. Lowering the resolution doesn't do anything for some reason either. Last month when I played Dota 2 I'd be stuck at 58-60 fps all game on max settings.

I doubt I have a virus I used my avg to find out, and systems clean. Right now I'm currently benchmarking to see whats going on but if you guys have any suggestions to help me out I'd greatly appreciate it.

(I just recently overclocked my cpu, and that doesn't seem to help out much either.)