Overheating (?) GPU

Hello Bocear,

Thanks for visiting Apple Support Communities. We understand that your iMac is overheating while started to the Windows OS. While it's hard to know what's happening exactly, we can help to narrow it down. Does this also happen when started to macOS? If so, reset the System Management Controller (SMC) to see if that helps. Here's more information about the SMC, and how to reset it: How to reset the SMC of your Mac

You'll also want to be sure that all macOS and Windows updates are installed: How to update the software on your Mac

If you're still having an issue, see if Apple Diagnostics reports anything:

Use Apple Diagnostics to test your Mac

Apple Diagnostics reference codes

Keep us posted.

Take care.

Hi,

When you reset the SMC, it should be done with all wired peripherals disconnected (printers, scanner, camera, etc...) and be done a minimum of 2-4 times as the SMC does not always reset after the first time, doing it multiple times works if the issue is related to the SMC.

For Macbook Pro if SMC and NVRAM and PRAM resets not resolve the issue install “Macs Fan Control”, set Left and right side Sensors Based on (locate your GPU model > Apple icon > About This Mac > System Report > Graphics/Displays > Chipset Model) e.g., Intel HD Graphics 630, click Sensor-based value > select chipset model, tweak lower and maximum temperature values (default Celsius can be changed to Farenheit in Macs Fan Control Preferences) e.g., 28C to 37C, in Preferences check Autostart minimized with system). Slight increase in fan noise at peak graphics usage.