Battlefield 3 FPS drops 7850 2GB

Hey guys,
So I got the sapphire 7850 2GB with the i5 3450 (not OC but at full load CPU will reach frequencies of 3300 Mhz).
I have had this computer for about a month now and I played BF3 just fine with pretty high graphics at 1920X1080 and didn't have any FPS drops.
Suddenly I am getting some major FPS Drops very often. They are very quick, I mean it drops but then comes up again, but its noticable. The game like gets stuck for a half a second then comes back again to average FPS. I checked the CPU and GPU preformence while playing with the command "render.prefoverlayvisible 1" and I saw that every time I get those drops the GPU and CPU jump out of the chart a lot then come back to normal..... (the chart measures usage of GPU and CPU).
I checked with HWMonitor what is the highest temperature the GPU and CPU gets to and the temp is pretty solid. GPU - 66 Celsius (max temp) CPU - 57 Celsius (max temp)

I just doesnt understand what causes those drops....|

Also I got a 8GB of RAM 1333MHZ and a Blue Caviar 1GB western digital hard disc.
with a very quality 550W PSU.....
Please help me!!