Question PC doesn't shut down completely; fans keep spinning and lights remain on

[Monnq]

Hello. As of yesterday, I am experiencing an issue where my PC doesn't fully shut down. The fans keep spinning, and my RGB lighting remains on and all I've got left is to hold power button for like 7-10 secs to definitely power it off. I'm using Z690 UD DDR4 motherboard, paired with i7-12700k. My PSU is XPG's Core Reactor 850W, I'm on Windows 11. So far, I've tried:

* resetting BIOS to factory settings

* replacing BIOS battery

* reinstalling older BIOS version (I was running on F28 and downgraded to F27 through QFlash Plus)

* disabling Fast Boot under Windows settings, along with disabling hibernation, PCI-E power management under Control Panel > Power Settings

* tried running sfc /scannow and DISM restore health commands

* tried updating chipset drivers

* played with BIOS settings, especially enabled ErP

I've also tried installing a fresh Windows 11 copy. None of steps above helped. Another thing I've noticed is that when I restart my PC, either by doing it from the OS or by pressing Reset button on my case, the computer doesn't restart normally. It first powers off completely, then after a second or two it powers up. I will be grateful for any tips.

 

[Ralston18]

PSU = XPG's Core Reactor 850W

How old? Original to build, new, used, refurbished?

History of heavy use for gaming, video editing, or even bit-mining?

Is it possible to swap in another known working PSU for testing? (Remember to use only the data cables that come with the test PSU.)

 

[Monnq]

I bought it in November 2021 when I was upgrading to 12700k, along with aforementioned Z690 motherboard. I was mostly using this setup for gaming. I am considering buying a new PSU for testing and see if the problem is with my current XPG or with motherboard.