If I play in windowed mode...

#1 - May 22, 2013, 2:05 p.m.
Blizzard Post

… my CPU and GPU fans stay pretty quiet. If I play full-screen, they’re spinning like dervishes. My screen is stretched so it fills most of my monitor.

I’m just curious as to why this would be.

Are my chips working harder in full screen rather then having, effectively, windows overlaying the game.

#3 - May 22, 2013, 5:36 p.m.
Blizzard Post

Hi Flatley – Generally your fan speeds are controlled by the temperature of your CPU/GPU. When playing in Fullscreen mode, your CPU is working a bit harder, getting a bit warmer, and thus needing to be cooler.

As Ilithis Mithilande suggested, MSI Afterburner is a great application for monitoring GPU usage.