PC won't turn off immediately after Windows shut down

Gessler555 · August 4, 2023

My old PC was bricked and I just bought a new (as in, not used) Gigabyte H81M-H Rev2.2 motherboard and a used i5-4590 to tide me over until I build a new one.

The PC works fine...just that when I shut down Windows, the display goes out (shows the "HDMI No Signal" message as it should) but the lights & fans in the tower (including CPU fan) continue to run for a good 20-30 seconds before shutting down.

While this is happening, I also noticed that the power LED on my monitor indicates that it's intermittently getting a signal via HDMI. The light is supposed to be white when in use, and orange when there's no signal. Typically, when I shut down Windows it should display "No signal" on screen and the power LED should go to orange and stay that way. But now its intermittently turning white, and then orange, then white again. It does this until the Motherboard finally shuts down.

What could be causing this and should I be concerned? Is this a power delivery issue or a firmware issue?

I'm using a Corsair RM850x 80+ Gold power supply. It's from my old build and is about 5 years old. The PSU gets power through a UPS.