GIGABYTE x570 aorus elite
Amd Ryzen 5600x
Enermax Aquafusion 360 Water cooler
I wanted to upgrade to w11 so I flashed latest bios and then when I booted up, cpu temps were steadily rising to 100°C and then my pc would turn off.
What i have tried:
1. Flashed bios back, didn't work.
2. Flashed some random BIOS in between those two, didnt work.
3. Took fan cables from the controller and plugged them into MBO directly, didn't work.
Enermax has a reputation of their AIO going bad.
Sounds like your Enermax AIO is not working properly or it isn't installed correctly or is defective.
Check to make sure the pump is running at its rated RPM speed, you can feel fluid running through the tubings, The input tube to the processor should be slightly cooler than the output tube from the processor.
The Radiator fans are running at maximum when it starts to overheat and there is no air flow obstructions to the fan and radiator.
Your Ryzen if it went over 100c shut down before it would be damaged from overheating. The Maximum Operating Temperature for your processor is 95c. Obviously once it reached 95c it started to throttle but couldn't keep the temperature at 95c or below and once the temperature reached a certain level it shut down to prevent damage.
to eliminate your Enermax AIO, I would replace it temporarily with a Air CPU Cooler rated above 65 watts TDP to see if your processor keeps overheating. Most likely it won't.
I would open a Enermax AIO Support ticket to see if your AIO needs to be RMAed or not if it is still under warranty.
As far as I am aware BIOS settings wouldn't cause a CPU to overheat like you described it.
Besides when you flashed your BIOS it was set automatically to factory default so if it is a BIOS setting causing the issue it should have fixed it when you flashed your BIOS again.
Whenever a CPU overheats it is due mainly to a defective or improper installed CPU cooler or a defective Thermal sensor either on the processor or motherboard.
Also improper overclocking or overclocking without the correct CPU Cooler to maintain it from overheating can cause the overheating also.
It was the headers..
I tried switching headers and concluded that the pump is working only when I connect it to cpu_opt header, but don't know why is that and why all of the sudden? Bios update shouldn't have affected it...
Agree with @elstaci
Plus, any 360 AIO would be overkill cooling for a 5600X. So, either a defective AIO or needs remounting.
But, I know you said your problem started when you updated the BIOS. Maybe the update changed or added features to your fan header settings. Check fan/pump option, 3pin-4pin settings, speed, etc.