PC randomly turns on and off

[Meowster]

Hi,

I have recently built myself a retro Windows XP machine just to play some older games but recently, it started turning off and on randomly. I checked the PSU and it was good. It behaves almost as if the power button presses itself.

Can someone please help me diagnose the issue?

[Bombastinator]

This sounds to me like something where details are going to be important.  

[Meowster]

1 minute ago, Bombastinator said:

This sounds to me like something where details are going to be important.  

Do you mean specs or something else?

[Bombastinator]

Just now, Meowster said:

Do you mean specs or something else?

I was thinking more about the particulars of the off and on thing, but perhaps.  Old machines sometimes have age issues where stuff simply wears out, or old/new things incompatibilities or things particular to their vintage.  Basically there’s very little data to work with.  It could be working then off/on or it could be “I turned it off, walked away, and suddenly it was on”. Working, then off/on could be a crash for example.  Just because something looks like it’s off (black screen, no fans) doesn’t mean it is.  

[Meowster]

3 minutes ago, Bombastinator said:

I was thinking more about the particulars of the off and on thing, but perhaps.  Old machines sometimes have age issues where stuff simply wears out, or old/new things incompatibilities or things particular to their vintage.  Basically there’s very little data to work with.  It could be working then off/on or it could be “I turned it off, walked away, and suddenly it was on”. Working, then off/on could be a crash for example.  Just because something looks like it’s off (black screen, no fans) doesn’t mean it is.  

So this is the thing it does: I power it on, I start doing something on it like installing a program. Then I might launch the program and it works for a little bit and then it gives me the "Windows is shutting down screen". Then randomly at night it might turn on as if the power button was pressed. This whole thing doesn't only happen on windows, it also happens on Ubuntu linux and the BIOS

If you want the specs then here they are: Gigabyte OEM Motherboard, 1GB DDR RAM, Onboard Intel Chipset graphics + ATI Radeon 9250, Intel Pentium 4 540 CPU

[Bombastinator]

10 minutes ago, Meowster said:

So this is the thing it does: I power it on, I start doing something on it like installing a program. Then I might launch the program and it works for a little bit and then it gives me the "Windows is shutting down screen". Then randomly at night it might turn on as if the power button was pressed. This whole thing doesn't only happen on windows, it also happens on Ubuntu linux and the BIOS

If you want the specs then here they are: Gigabyte OEM Motherboard, 1GB DDR RAM, Onboard Intel Chipset graphics + ATI Radeon 9250, Intel Pentium 4 540 CPU

So the walk away one.  Orderly shutdown is not a crash, and OS independent.  Could possibly be something win and Linux share.  Wow. P4.  I went p3 to Qseries I missed p4 entirely so I got nothing for vintage specific stuff myself.  That’s some old old stuff.  There are posters here younger than your machine.  Button thing is not impossible with that kind of age, but it could be something just being worn anywhere in the chain of power delivery.

[Meowster]

2 minutes ago, Bombastinator said:

So the walk away one.  Orderly shutdown is not a crash, and OS independent.  Could possibly be something win and Linux share.  Wow. P4.  I went p3 to Qseries I missed p4 entirely so I got nothing for vintage specific stuff myself.  That’s some old old stuff.  There are posters here younger than your machine.  Button thing is not impossible with that kind of age, but it could be something just being worn anywhere in the chain of power delivery.

I guess the system is pretty old. However, if I take out the button and just short the 2 pins on the motherboard, the system never shuts down. Could this indicate a broken button or something else? I'm no expert in small electronics

[Bombastinator]

1 hour ago, Meowster said:

I guess the system is pretty old. However, if I take out the button and just short the 2 pins on the motherboard, the system never shuts down. Could this indicate a broken button or something else? I'm no expert in small electronics

I’m not either.  All the button should do is short those pins. This implies the problem is not the button but higher up

[Meowster]

20 hours ago, Bombastinator said:

I’m not either.  All the button should do is short those pins. This implies the problem is not the button but higher up

Found the issue: The HDD PCB was shorting to the metal case of the HDD, don't know how that was possible but somehow it was enough to kill the system. Its an old Quantum Fireball 40GB Drive