I have recently replaced my old Corsair TX650M PSU with a new CoolerMaster Silent Pro Gold 800w PSU. With the old PSU when I turned off my computer from windows it would shut down and everything would turn off. The lights would turn off and the fans would stop turning. With my new power supply when I shut down windows It shows the usual shutting down dialog then my two monitors say "no signal" and turn off. The weird part however is that the lights stay on and the fans continue spinning forever until I manually hold the power button in for 4 seconds then finally everything shuts off. How can I emulate the previous behavior?
I was able to solve the issue. Here's what I did in this order:
When I sent the shut down command from Windows, the PC completely shut off as usual. I was able to detect that this was a hardware issue rather than software (at least on the OS level) by creating a USB boot-able version of Ubuntu. When I tried to shut down Ubuntu and had similar errors I knew nothing was wrong with the OS. I was able to narrow down my search queries and put together these steps. From what I can tell it appears this is an issue with ASUS motherboards. I hope this helps anyone who stumbles across it!