Hello, I've been getting FPS drops with my new Asus Direct CU II 7870 with pretty much any game I play. I can play at about 60 FPS on BF3 then randomly drops to 15-20 FPS for about 10 seconds then goes back up to 60. This actually happened to my old card,the HIS 6850, but then it stopped. Could it be related?
Here are my specs...
Asus Direct CU II 7870
AMD Phenom 2 x4 955 @ 3.3Ghz
12GB of DDR3 RAM @ 1600Mhz
What you are describing is very common with systems that have heat and/or power issues. Your PSU should be okay for this rig, your CPU is getting hot and might be clocking down to prevent damage and then spinning back up once the CPU cools a bit.
If you don't know, likely you are using the one that came with your AMD CPU. Those tend to provide minimal levels of performance over time. Adding a stronger GPU can put more of a load on your CPU and generate more heat. You could also have a lot of dust built-up in the CPU heatsink that can be removed with some compressed air.
BTW, are you overclocking either the CPU or the GPU? If so, stop and see if the drop continues.
In addition to the suggestions that COL has suggested, I suggest seeing what your CPU voltage is set to. Some cheaper boards put the CPU voltage to its max allowed for whatever reason. Something worth checking.