Windows 7: Random FPS lag while playing games

I've been playing games such as Counter-Strike: Source for the past while, now. At first, the game would run fine at 40 FPS. And it did for a while. Now, the game frame rate will randomly drop to 10-20 FPS. This isn't chronic, as it will go away after about a minute. I've kept my CPU temp and usage windows open on another display and it shows no spike in usage or temperature during this time.

This plagues most of my games. Games like Counter-Strike: Source and Team Fortress 2, but not games like The Binding of Isaac or Realm of the Mad God. I already went through several troubleshoots, such as closing background programs and checking drivers (led to no avail).



This is becoming more and more of a problem, can anyone help?

1st u have to determine what is cause. Game or windows.

If its game, it can be only on specific server, settings, patch... ?
40 fps is kinda low for FPS games, try disabling v-sync, Antialiasing...

if it is windows... it can be... huh what cant be? :P

while i am playing PES2012, when song changes on youtube, i get lag for 10sec, but not in World of tanks...