The random crashing at low usage sounds very similar to an issue I had with my previous 5950x. There seems to be a real problem with 59{00,50}x’s where you either need to disable PBO (I think that’s the name) or bump voltages. After finding out it was a silicon lottery thing I sent my cpu right back to Amazon and the replacement has been perfectly fine from first boot (outside of figuring out the upper memory clock for 4 dimms)