Loosing FPS, then regaining it.
Hello I am new here. Lately I have been playing Call Of Duty 4 for the PC. I have my fps maxed at 250, which I usually achieve. However lately, I have been loosing say 100 fps suddenly, then it goes back to 250. Could someone please advise me on what the problem is? Overheating? P.S sorry if this is in the wrong forum.