My PC reboots instantly when trying to install Windows 10

What about offline System File Checker:

How to Run SFC OFFLINE (System File Checker tool) - wintips.org - Windows Tips & How-tos

It points so strongly to hardware that I would cross-post this at Tom's Hardware where the best experts are for hardware:
https://forums.tomshardware.com/

I gave several other things to try, please refresh the browser as I have added more.

The drivers for GPU are on the hard drive so were removed in the test that reproduced the restarts. You can remove and reseat the GPU which sometimes works.

I added the fixes back for random restarts exactly because of the original cause of this being the Update. Did you ever get a chance to System Restore or uninstall the Update, even from the Repair Mode?

How to use System Restore on Windows 10 | Windows Central

Advanced Startup Options (WinRE Repair Mode to System Restore and Uninstall Updates, also enter Safe Mode)

See if it's stable in 1) Safe Mode with Networking (so you have internet) or 2) Safe Mode, accessed by one of the illustrated steps in this guide: https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10. You will need to use your password to get into Safe Mode as a PIN is not accepted.

The fact it did the same problem behavior when you removed the SSD means it doesn't involve Windows or the SSD, and is caused by the remaining hardware.

Do you have another PC you can install the SSD by itself and install Windows on it. Move it back to the problem PC and see what happens. Windows 10 is remarkably adaptive to different hardware without needing adaptive restore. If it will start it will swap out all drivers, requiring several restarts. You may need to run Startup Repair or in rare cases a Repair Install to work out kinks, but usually not.

Further troubleshoot the hardware:

How to Troubleshoot Computer Hardware Problems

How to test for hardware failures in a computer

If you can get Windows to stabilize try these fixes for random restarts:

https://windows101tricks.com/windows-10-freezes-restarts-automatically/

https://techcult.com/fix-computer-restarts-randomly-on-windows-10/

https://www.thewindowsclub.com/windows-computer-restarts-without-warning (Avoid ad links which intrude into editorial copy, especially avoid Restoro and Reimage ads)

https://troubleshooter.xyz/wiki/fix-computer-restarts-randomly-on-windows-10/

https://windowsreport.com/random-restart-windows-10/ (Avoid ad links which intrude into editorial copy, especially avoid Restoro and Reimage ads)

https://www.reddit.com/r/buildapc/comments/8zd1rv/random_restarts_on_new_pc_build/

https://support.hp.com/us-en/document/c03413399

https://howtofixwindows.com/windows-10-computer-restarts-unexpectedly/

Hello Greg,

Sorry for the delayed response, needed time to run through everything. My responses in Red.

Did you try removing all but one RAM stick, then swap it to see if the behavior stops?
Yes I did try this. I also ran both sticks individually through memtest86 for 8 passes each. Same rebooting behavior. Even when i tried 2 brand new sticks of RAM

Unplug everything except the CPU, GPU and PSU and see if it stabilizes, then add back the other components to see what happens.

For this one I am not entirely sure what you want plugged in. Besides the drives what else is there to have unplugged? Unless youre referring to say the keyboard,etc. I did unplug my wireless mouse and did the below troubleshooting with just the keyboard. So the only external devices are the keyboard, monitor and usb installation

Unplug the SSD and other drives, boot into the media to see if it stabilizes.

I removed the m2 SSD and attempted to boot with just the media usb. Out of about 7 attempts 4 reboot before i hit windows installation screen and 3 i was able to enter the install steps, but it reboots randomly. Once at first screen, at terms of agreement, and at windows version. I can however sit on this screen forever if it loads, as long as i dont progress or click anything.

Unplug all but SSD drive, See if you can boot into Command prompt reached by pressing Shift + F10 on first screen or on second screen choosing Repair Your Computer > Advanced Troubleshooting Options.

Type DISKPART
LIST DISK
SELECT DISK # (replace # with SSD Disk #)
CLEAN
EXIT

Now see if you can install Windows, Custom install, select Unallocated Space at drive selection screen, then select Next to let the installer create and format the needed partitions and begin - which makes it foolproof.

I reinstalled the m2 ssd and after it self rebooted in the loop 2 or 3 times i was able to enter the Command Prompt and clean the drive. I exited the terminal and stepped through the installation successfully. I then restarted as prompted and it then goes into the "Starting devices" screen and then freezes and enters the reboot loop where it starts up, shows the ASUS logo and spinning dots, freezes and reboots. Sometimes it will show the BSOD, and sometimes it will show a restart error popup saying that something went wrong and it needs to restart to finish the installation. I tried this two times struggling to get to the installation screen before rebooting and both times i successfully installed windows 10, the reboot loop behavior was the same.

Report back all results.

Hi Migz. I'm Greg, 10 years awarded Windows MVP, specializing in Installation, Performance, Troubleshooting and Activation, here to help you.

Did you try removing all but one RAM stick, then swap it to see if the behavior stops?

Unplug everything except the CPU, GPU and PSU and see if it stabilizes, then add back the other components to see what happens.

Unplug the SSD and other drives, boot into the media to see if it stabilizes.

Unplug all but SSD drive, See if you can boot into Command prompt reached by pressing Shift + F10 on first screen or on second screen choosing Repair Your Computer > Advanced Troubleshooting Options.

Type DISKPART

LIST DISK

SELECT DISK # (replace # with SSD Disk #)

CLEAN

EXIT

Now see if you can install Windows, Custom install, select Unallocated Space at drive selection screen, then select Next to let the installer create and format the needed partitions and begin - which makes it foolproof.

Report back all results.