Hi,

Recently I started to encounter a new issue with my 3 year old PC. It sometimes turns off randomly, then turns back on after a few seconds. It can happen anytime, even when OS has not booted yet. Sometimes it turns off and on repeatedly, like struggling to keep powered on. Overheating should not be the issue because it has happened right after I turn ir on for the first time that day. Nothing new has been added or installed recently. Also not overclocked.

Could it be a faulty PSU or other hardware?

Thanks

Sure. When it does come up, look in the bios for a power resume on loss mode. Turn that off. Such a PC has priors and tracked to heat, PSU, motherboard and other parts. The first time of the day points me more to the old BAD CAPS PLAGUE (see google) or a PSU that was barely big enough in the first place. PSUs lose capacity over time so new PC techs often must learn about that.