I plugged my PC right into the wall 3h ago and haven't got a problem yet, lets give it more time.
I read my Mobo manual and rechecked my connections, everything seems OK.
Test the memory with memtest86+ for errors, so we can exclude that as a cause.
Just done that, passed 1 time, but I did that 3 month ago and let it run over night, passed like 6 times, no errors.
So, excluding RAM, could a deffective CPU / Mobo / GPU cause theses weird random crashes (remember the distortion and high-pitched noise) or would the PSU really be the problem if the crashes happen again?