PC turning off

[fossyant]

Also check graphics card isn't overheating. Could also drop some lube on the fan spindle - would need to remove fan(s) off any heatsinks, and lube (finish line pro road ceramic is good )...

 

[SavageHoutkop]

The PSU is well overspecced for the unit and it would either work or not wouldn't it, it wouldn't work but not display, which is what is happening.

No, PSUs are very very odd beasts. We've recently discovered that Mr SH's has a minimum operating temperature of about 10degrees, below which - wait for it - first the graphics go odd (blocky things on the screen); and then things like not booting properly, no beeps on boot; nothing happens when push power button... (aim a heater at it for 10 minutes though and it works like a dream...)

Also, sometimes (I'm not by any stretch of the imagination good with 'electrics') I think the capacitors need to charge up - if you have a faulty capacitor it could be the problem.

I've also had one (literally) blow up - large bang and smell of burning - capacitor exploded.

If it's not pumping out the voltage the MB / CPU are expecting... anything can happen.

If it were CPU overheating I'd hope it let out fatal beeps before just turning off.

 

[661-Pete]

What make of PC is this, out of interest?

I had something similar - but not quite the same - on my PC at work (Dell desktop, only about 6 months old). Was difficult to turn off, kept on powering on again but the light in the on-off switch lit yellow instead of the normal green. Nothing at all on the monitor. The only way to completely power-off the machine was to pull out the mains lead, and then powering back on was a bit iffy - sometimes it booted up OK sometimes it went to this 'yellow' state.

Since this was a company machine we got the Dell man (should that be "Dell-Boy"? ) in to see to it. He replaced the PSU and the motherboard, but when he fired it up the new motherboard he'd brought turned out to be a dud, so he put back in the old motherboard but left me with a new PSU. That seems to have fixed the problem.

So in my case it was the PSU. Don't know how much help this is to you.

 

[Crackle]

I made it, from bits. I made two, one for Crackle1 and one for Crackle2. Crackle1 seems to break his with exciting regularity.

Anyway, I've been monitoring the CPU all day with not a flicker. My suspiscions are heading towards the graphics card now.

 

[Crackle]

No, PSUs are very very odd beasts. We've recently discovered that Mr SH's has a minimum operating temperature of about 10degrees, below which - wait for it - first the graphics go odd (blocky things on the screen); and then things like not booting properly, no beeps on boot; nothing happens when push power button... (aim a heater at it for 10 minutes though and it works like a dream...)

Also, sometimes (I'm not by any stretch of the imagination good with 'electrics') I think the capacitors need to charge up - if you have a faulty capacitor it could be the problem.

I've also had one (literally) blow up - large bang and smell of burning - capacitor exploded.

If it's not pumping out the voltage the MB / CPU are expecting... anything can happen.

If it were CPU overheating I'd hope it let out fatal beeps before just turning off.

You could be right. The CPU is staying well within temperature and the Graphics board checks out as fine using a number of utilities. I discovered also that when it turns off and you turn it back on and nothing happens. If you then remove the power from the supply altogether and plug it back in, it then comes on as normal.

 

[Debian]

Just seen this thread.

I'd say PSU, almost certain.

 

[Crackle]

Just seen this thread.

I'd say PSU, almost certain.

I'm off to get one tomorrow. Glad I asked on here, I was convinced it was the CPU before all the advice.

 

[Crackle]

Well, not the PSU. I've come full circle back to the processor.

 

[rh100]

Did you check those capacitors I mentioned? If any have bulging tops or are leaking then the motherboard is shot.

 

[Crackle]

Did you check those capacitors I mentioned? If any have bulging tops or are leaking then the motherboard is shot.

I did but I'm going to go back through everything again. I've borrowed a processor now to swap out, so that should confirm the diagnosis.

 

[trustysteed]

have had quite a few laptops display this system and it's been caused by the heatsink not making enough contact with the processor to disperse the heat properly. so the system shuts off as a safety measure. cleaning off the old heatsink paste and applying new stuff and ensuring contact is solid has resolved the issue.

 

[SavageHoutkop]

I always thought if the CPU overheated it would emit frantic beeping (well, the motherboard would emit the beeping) before shutting down?