Tech support- pc stalls at black screen for 10 minutes during startup

My Win 10 pc started having this mysterious problem about a month ago. Directly after the very first image I see on turning the pc on (that image is my hp omen logo with windows circling dots animated below) the screen goes black (monitor on but displaying just black) for a very long time, 10-20 minutes. There is no obvious activity, no hard drive sounds, fans sound normal, like it's literally just counting down a timer.

Then it just comes on and acts completely normal until I turn it off again.

I haven't found anything obvious in the event logs and I'm not sure where else to look. I have reinstalled windows thrice in the last month. I hadn't realized that the problem was a hang and not a complete failure so I reinstalled. The problem takes a bit to return when I do that, about a week.

I suspected Windows updates so I froze those, I think I have ruled them out though I did allow some updates (Like Xbox app and services) through recently, and the issue subsequently returned. I saw a lot of Oculus related spam in the event logs and uninstalled it but the problem remains.

I'm not too sure where to go from here. No scans are finding bad hard disk sectors either. Thoughts?

Does it take a long time to wake up from sleep also, or just a hard reboot?

I never do sleep so I had to try it for the first time. It seemed to work fine.

Hmm.

Can you reboot in safe mode and see if it still hangs? My guess is it will.

Are you using an AMD GPU? There is a power setting in the registry which causes AMD GPUs to hang on startup, used to give me the exact same symptoms even on an SSD. After disabling it, Windows would boot in about 5 seconds.

Edit: On the off chance I'm right, go into regedit, search "EnableULPS", and once it pops up change the value from 1 to 0.

Thats an interesting problem to have PurEvil. I'm on an Nvidia GPU though.
This morning Windows booted fully in less than 3 seconds. It was astonishingly fast and leaves me completely baffled. The day before it took the 20 minutes again and I didn't try anything that day that I believed would have an effect.
It also doesn't do it on sleep/restart, or even power down/power up after 10 seconds. Only overnight and only sometimes. (So safe mode is hard to try too)

Remove components from the computer leaving only the bare essentials to see if the problem persists. Then slowly add components back in until you find the culprit.

It just magically stopped doing it. I fully expect it to start again at some point but its been about 2 weeks.