GTA 4 Loading lag on 7950?

Hi guys:

my spec:

xfx 7950 dd
i5 3570k
16gb ram


I just got gta 4 today and I have noticed something strange, the gameplay was mostly smooth on 40-50 fps on maxed out, but sometimes when looking at open envoriment, my fps would drop down to 30, sub 30 when fraps is on, and then bounce back up again like its nothing.

same thing happen with skyrim but these drops don't exceed 2-1 fps, 3 at most.


any ideas?

thanks