CPU fan ramps up and down

[Milos_10]

So when im playing a game and exit after some period of time ,the fan speed lowers but with frequent rampups and rampdowns
why halp

 

[Sedivy]

There may be stuff happening in the background you're not aware of. Open your task manager (ctrl+alt+delete->select task manager), go to Details tab and sort by cpu usage. Minimize it when nothing's happening but it gives you an icon to quickly click on and pull up when you do see a ramp up in your fans. Just check which process it is that's suddenly ramping up your cpu.
Probably windows update, or something with antivirus, or some sort of caching, or even steam syncing your game to the steam server. Could be a bunch of things, but this way it's easy to check if you're unsure.

 

[Milos_10]

Could it be a defective fan cuz its runing on 1600RPM when idle?
Room temp is like 30C cuz its summer.