Old PC restarting on its own and not booting up properly (Fixed)

[Duck_Tape]

This is fixed I am only posting this as a help to others who may experience this.

No pics, it's more of a story...

Old PC (bought 2009) P6T SE motherboard with intel I7 Gen 1 processor. There have been upgrades over the years (Better Graphics, More RAM, SSD as boot drive)

This PC has been unused for a while but I decided to revive it for one of my kids.

Part of the reason I replaced this PC was I suspected there was a PSU fault combined with its age. The PC had issues starting, The PC would power on but not boot up windows, there was no display etc. but you knew it was working as the fans were running this required turning the PC off and on a few times before a successful boot to windows.

The last upgrade was two weeks or so ago which was a new PSU.
(Corsair RM650, RM Series, 80 Plus Gold Certified, 650 W Fully Modular ATX Power Supply – Black)

All was well till 27/08/21. I turned the PC on and it got stuck in try to boot, restart cycle.

I turned it all off, waited a few mins and tried again. This time the PC tried to start then after a few seconds rebooted, on the second try to boot after a few seconds the CPU fan and case fan keep going but the PSU fan stops. Nothing is working it’s not getting to the BIOS and there is no video signal.

So not quite the same issue, as before but close.

I unplugged every device and drive leaving just the CPU and graphics card connected but the same problem. I am starting to think has the new PSU developed a fault. Everything was fine for about two weeks.

So I spent a few hours on google and YouTube looking up similar faults to this. Lots of explanations of how this is a difficult process to track down the fault as it could be any number of components that are causing the problem.

I came across some comment to another post “Have you changed the CMOS battery, that’s the first thing I would do before pulling everything apart”)

That had not occurred to me, my previous experience of CMOS battery failure was the PC would boot but go straight to the BIOS to set the date and time, boot drive. Every time you booted up the PC till the battery was replaced.

I needed to take the graphics card out to access the battery, I actually had a spare battery as it’s the same one for my car key fob.

New battery in, graphics card back in. and success, the PC boots to the BIOS.

Everything else back in place, boot to the BIOS, reset the clock and boot drive order, reboot, 30 seconds later I am logging into windows again.

It could have been the CMOS battery all along but the new PSU is quieter so it's still a win buying it.

[Someone-Else]

Was it a cr2032?

[Duck_Tape]

I think it was, let me check the card the other batteries are on (I bought a pack of six)
Back in a few mins

[Duck_Tape]

still looking, they are not where I thought they were.

[Duck_Tape]

Hi yes I can confirm it was a CR 2032 button cell