I've been having this issue for a while, I even posted something a while back, thinking the problem was caused by my graphics card. I'm getting weird FPS drops in most games. BF3 is unplayable like this, it stutters like crazy. The FPS in MW3, GTA IV, or Crysis 2 just drops to a unplayable/crappy state. Turns out it wasn't the graphics card. I bought a new one and it didn't help me at all. Now I'm wondering if my CPU is broken or my motherboard. I've switched my CPU to a AMD Athlon II X2 215 and the FPS drops were gone, it's just overall bad performance. I'm just wondering if the MB doesn't like the CPU, or the other way around. I'm using the newest BIOS revision for my MB, wich is an ASUS M4N68T-M LE V2. I checked the ASUS website for CPU compatibility. The 125W version of my AMD Phenom II X6 1055T is officially supported.
Here's my specs.
CPU: AMD Phenom II X6 1055T 125W
Graphics: AMD Radeon HD 6850 (Newest Drivers)
Mobo: ASUS M4N68T-M LE V2 (BIOS Revision 0902)
PSU: Corsair CX500
Windows 7 Ultimate x64