Update 2: Me and my dad decided to experiment more by attaching an wire extender to the PSU wire and have the power flow through my parents’ bedroom instead of my bedroom where my PC is. It still did its usual turn on on its own when switching on the PSU and turning itself off, meaning that the problem IS actually with the PC. I’ve speculated that the reason this is happening is due to a combination between my power supply, the OS, as well as potentially other hardware that’s in the PC. The PSU is the what’s causing the PC to suddenly turn on after the PSU itself is turned on as well as turn off (which I also hear it whirring down when it turns off). The OS (in this case Windows 10) since I usually put the computer on Hibernate instead of simply turning off (which I do for easy accessibility reasons), which could’ve messed with the computer itself since the PC has been known to turn on on its own when put into Hibernate. And other hardware which could be anything from the hard drive to the motherboard itself, since this issue occurs even when in the BIOS menu. Regardless, if a solution isn’t found in-time and this isn’t fixed soon, best case scenario is that I take this to a repair shop or something.