Old PC starts and shutdown randomly within 2 seconds to 1 hour

[amish]

So as I have been discussing in some other thread. I am planning to purchase new PC.

But before that I am just testing the old PC which I almost NEVER used. (harddisk used only for 45 hours in total)

I started this PC after like 8-9 years. But it looks completely brand new.

It has 3 fans in total. CPU Fan, Cabinet fan and PSU fan.

Here is what happens - randomly:

1. I press power button, all fans start and switch off in 2-3 seconds (without beep sound)
2. I press power button, all fans start and switch off after 5-10 seconds (after beep sound)
3. I press power button, all fans start and OS boots (and then switches off from 2 mins to 1 hour)
4. After switching off, it does not restart by pressing power button OR pressing reset button
5. To restart either I have to turn off/on wall switch OR press power button for 7-8 seconds, release it and then press it again.

I was able to install Linux yesterday and then it stayed on for almost 1 hours (or may be little less) and then switched off directly.

I believe it is SMPS problem but just wanted to ask if there could be any other reason, like motherboard going bad etc.?

Thank you.

Photos attached - in case someone wants to have a look.

 

[amish]

There are three fans in the system... 1 is on CPU, other is inside SMPS, 3rd is extra fan attached to motherboard and cabinet.

All 3 fans shutdown together.

I wonder why SMPS fan should shutdown?

Not tried changing RAM slot but I doubt thats the issue, but I will try.

There is no external graphics card.

 

[ijsa]

Wild guess..... Are you having any insulation/ space between Motherboard and Motherboard holder in box.

Try booting the motherboard out of box without ram and other things storage etc.....

 

[amish]

what is motherboard holder?

 

[pujaari]

Can try one more thing though seems unlikely that will resolve the issue.. Reset bios to default ..check if CMOS battery hasn't died...could also be a case of faulty power switch..google ways to check faulty power switch

 

[ijsa]

what is motherboard holder?

The plate on which you screw up the motherboard in box.....

 

[amish]

Can try one more thing though seems unlikely that will resolve the issue.. Reset bios to default ..check if CMOS battery hasn't died...could also be a case of faulty power switch..google ways to check faulty power switch

CMOS battery may be dead (not used machine from many many years).

But I have run other PC in past where CMOS battery was dead. Its just that system time always goes back to epoch. But does not shutdown the system. I dont think CMOS battery can shutdown the PC.

I checked power switch by removing it and starting system by pin shorting method. Since system still shutdown using that method, hence can not be power switch issue.

Wild guess..... Are you having any insulation/ space between Motherboard and Motherboard holder in box.

I do not know how much space should be there... I have never touched motherboard fixing ever since system was bought.

I will have to unscrew whole motherboard. Will do this weekend.

 

[ijsa]

What I meant was if there is some debris/ something else in between........ it might short/ earth the system...... and might result in auto shutdown....

just a theory....

 

[amish]

The PC is very clear (atleast to naked eye) because it was not used from years and I had it kind of tightly sealed.

There was atleast 2-3mm gap between board and bottom of the cabinet (because it was resting on something)

But when my thermal paste comes.. i will first remove the motherboard and test.

 

[amish]

So yesterday I removed whole motherboard out of cabinet and put it on wooden surface and started it.

But same problem, it would start and randomly shutdown. Sometimes within 2-3 seconds, sometimes within 3-4 minutes.

Then I put thermal paste on processor. But still same problem.

So in short I am still stuck right there! Its either SMPS or motherboard or may be in rare case processor?

What I do not understand is that SMPS fan also stops when machine stops, but power supply to PS2 keyboard remains on. Now keyboard is attached to motherboard so that means even if SMPS fan is off, motherboard is still getting power? i.e. even if SMPS fan is off, SMPS is still supplying power to motherboard?

Anyone has any clue?

 

[anubhav11]

Actually SMPS supplies multiple different volts seperately to the motherboard. So even on standby when the fan stops it is still providing volts. But the problem occurs when it is unable to sustain that output for some reason. I know installing a software on your pc will be quite tricky but if you can try installing hw monitor to check the power provided by the smps, that would should a good picture about the health of your smps and even your motherboard stats. if you are a DIY person you can check smps with a volt meter on its output ports via the wiring diagram shown on it.