Dramatic FPS drops

I normally get anything from 80fps/ 150fps ( doesnt change even if i change settings)

every now and then sometimes more than others it will drop down to 1 for a split second making hardcore unplayable.

M5A97 pro mobo.
Fx6100 3.8ghz
MSI 1ghz ed 7770 (13.1 driver)
8gb amd performance ram 1600mhz
WD 320gb hdd (not sure on speed)

Anyone else having this problem?

I've had a little look through the forums found no fixes so far.

Thanks in advance