One morning this week my 2014 PC suddenly had difficulties to boot up, and then stopped booting altogether. I stripped down the whole thing and reinsterted everything, tested memories fully with memtest (0 errors), before I got the idea to give the power button a firm press and keep it there for a couple of seconds. This way it boots up every time. I switched power to the reset button on the mobo, but it also requires the same long firm press. Any ideas?