When I'm listening to iTunes audio with headphones, when the screen goes black after 10 minutes of keyboard inactivity the fan starts blowing like there's a sudden increase in processor usage. Sometimes it will slow down or stop for just a bit, but then pick up again. -- But if I touch the keypad and bring the screen to life again then the fan noise ceases.
I'm wondering what process could be running to be generating the extra heat when the screen is dark, and maybe how I can stop it. Obviously I can't see it happening myself because when I run Task Manager (Windows 10, by the way) the noise has already stopped.