GPU low use issue - fps drop

Hi all! I recently purchased a new Radeon 6950 and loved it for the last two weeks, but then this issue popped up. I am playing a game, and suddenly I notice my GPU fan is slowing down and my frame-rate drops considerably. I have noticed the issue in BF:BC2, TF2, and Stalker: Shadow of Chernobyl. I the third game I was able to resolve the issue by alt-tabbing several times, but this does nothing for BC2 or TF2. With Task Manager and MSI Afterburner monitoring I see that GPU utilization drops from 100% down to about 50%, and CPU utilization jumps up to 100%. I am using Afterburner to monitor temps and for the fan profile, but nothing is overclocked. Clock rates on the 6950 remain at 800mhz core and 1250mhz vram. In BC2 fps drops from about 50 to around 25, making it totally unplayable, and the drop is similar in other games.

Is this a driver issue or is my card faulty?

My system specs are as follows:

Phenom II X4 955 stock
Gigabyte 790X mobo
Mushkin 4GB DDR3 1333 Ram
OCZ ModXStream Pro 600W PSU
Gigabyte Radeon HD 6950
a couple of Seagate HDDs
Windows 7 64 bit Home Premium
running at 1920x1200 resolution
CCC 10.11 (8.790.6)

Your assistance is greatly appreciated!