Shuts down when idle

After 5 to 30 minutes, if there's no workload going on (CPU turbo mode disabled), I get a black screen and my Macbook shuts down.

I tried a lot of stuff: reinstalling macOS, forcing the fan speed to the max. Doesn't work.

Safe mode and bootcamp Windows works flawlessly (well the frequency is always 3.8ghz..).

At the moment I'm out of ideas and running a "while true; do; done" loop in the background at all times. Funny thing is, the moment I Ctrl+C my screen goes black.

However this is not ideal as it kills my battery and makes my laptop pretty loud.