sudden strange problem

Griff7520 · Wednesday at 12:38

Hi

Have a problem starting the pc. Its been running great but this morning I pressed start on case as usual but the pc would not boot. It did for a few seconds there was power there but it just switched off again.I had to press start several times before it actually started and once up and running its fine. Done loads of tests ie ram cpu etc etc but can not find a problem.

Its a new build and has been running great for 2 weeks. I unplugged everything and reseated all and still same problem. I tried different ram and still same issue.

Any ideas as to what this could be

I am thinking:-
PSU
Motherboard
case button
short some where

any help most appreciated

Mcnumpty2323 · Wednesday at 15:51

On/off buttons are momentary switches
Usually work or dont
So if power was there switch should be working
Unless its double clicking
And your power settings are set to shut down
With a single short push of power button
Which isnt normally the default
normally its a long hold on the button

You can Test by removing the 2 pin cable
And shorting out the 2 pins
Or if its more than a basic motherboard
It may have an on /off button on the board
So could at least rule out the power button

To rule out a short
Would have to assemble outside the case

You can paperclip test the psu
Though that just confirms basically it's working/not working
Doesn't mean it's working under load

No real test for motherboard
Other than try removing usb cables from the board
In case a short from front usb ports

Griff7520 · 2026-02-12T08:59:28+0000

Thanks for the reply. I ended up removing the motherboard and putting a z790 board in with A 12600K which I was planning to sell and everything is back to normal. I suppose the board or chip was faulty so Have sent them back to the rain forest. Didnt know which was the faulty part so sent both to be sure. May just stick to z790 for now

Mcnumpty2323 · 2026-02-12T10:09:06+0000

Yeah that's the problem
When you have an issue that isn't obviously
Going to be a certain component
Its very time consuming and frustrating
Swapping out parts
To see if it sorts it or not

Luckily you had the other
Motherboard and cpu to fall back to

Decoman · 2026-02-12T11:24:37+0000

*never mind I didn't read OP's post fully*

Decoman · 2026-02-12T11:26:48+0000

I have had one instance in the past, of being unable to power on the pc.

Turns out, there was a short circuit when I was fiddling with something, and the pc refused to power on. Never before I had seen something weird like that happening with a pc machine.
I thought in an instant I had ruined the motherboard, but as it turned out half an hour later, no apparent damage.

Solution was to disconnect ALL power cables and wall warts powering things connected to my pc, and then wait half an hour.
Then, and only then did the pc power on again.

Now that I think about it, I think now maybe OP's issue is caused by the bios resetting itself in ways, thus has to try boot up more than once.
Edit: Hm, but then, the power light should stay lit if it just reboots several times by itself.