Thermal throttling after Big Sur update

My 2015 i7 MacBookPro started to thermal throttle after the update to Big Sur:

• in previous system, the Mac went up to 90°C degrees before slowing down. And it would not thermal throttle at all. The thermal throttling temperature seemed to be 98°C degrees.
• currently it thermal throttles at 70°C degrees: the CPU frequency slows down to 800 MHz and GPU down to 200 MHz (as indicated by Intel Power Gadget)

This is all after I installed "Macs Fan Control" and this is after I set it to "Full Blast" which means 6100 RPM. I have already changed the CPU thermal paste.

How can I change the "thermal throttling" temperature to a higher value?

Solution 1:

The "problem" will most likely disappear if you turn off MacsFan Control.

I have experienced very similar problems when settings MacsFan Control to full blast thinking, this would ensure the coolest CPU temps possible. However, in my case kernel_task started to spike to a couple 100% of CPU usage which is very often an indicator for thermal throttling.

My suspicion is that when setting the fan speed with MacsFan Control your MacBook loses control over the fan speed and as it does not know what you will do next it starts throttling to avoid any problems.

When your MacBook controls the FanSpeed it knows it can adjust the fan speed and CPU/GPU power as needed, however, when you manually set the fan speed it loses part of its mechanism to ensure low enough temps for the Computer. It then plays it safe by throttling the CPU so much that it will definitely not be harmful in case you would e.g. suddenly completely turn off the fans.