I wanted to leave my computer running idle overnight, but whenever I turn off the monitor, the fans suddenly become much louder. The noise stops or changes when the monitor is on again. What could be causing this, and how can I troubleshoot or fix it?
3 Answers
It could simply be a coincidence, so check what the computer is actually doing when the monitor is off. Open Task Manager and look for unusually high CPU, GPU, disk, or memory usage. A background update, scheduled task, game, or other program may be making the fans ramp up.
Check whether a program is using the GPU after the display turns off. Some systems change graphics or power behavior when the monitor sleeps, which can increase fan speed. Updating your graphics drivers and reviewing your power settings may help.
It’s also worth checking for unwanted software, including a cryptocurrency miner. Run a full Windows Security scan and review Task Manager’s Startup and running-process lists. Make sure Windows Defender isn’t excluding any suspicious files or folders.

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