Computer suddenly loses power...

[Neo]

Hi All,
Just a few minutes ago my computer suddenly lost all power and rebooted.

This has happened a few times over the last couple of months.

This happened to coincide with a mysterious Firefox crashing issue that I had been experiencing and at the time thought it might have been related (I didn't know what was causing the problem then), here is a link to that thread:

http://www.pclinuxos.com/forum/index.php/board,19.0.html

Anyway I know this is incredibly broad but where do I start in trying to track down the problem?
I think it's hardware but don't know if it could be software based.

I built my own computer just over five years ago.
It was then that a friend from work introduced me to the world of Linux and I haven't looked back!

It has an ASUS mobo (P5WD2-E), an Intel D950 cpu that is overclocked by 20%, both cores running at 4.087 GHz (back then this was bleeding edge stuff and I had to overclock it to get it to run stable - I know it sounds weird but it's true), an Nvidia graphic card (don't remember the exact model number, I think it's a 7900 GTO or something close to that), good quality RAM (can't remember who makes it but it is one of the top brand names), I had two Western Digital drives go bad on me, just outside of warranty period so I had to pay to replace them both with new WD drives (or is it just one big one the same size as my two old ones?) - geese there was a time when I could quote all these specs in my sleep.

So any ideas as to where or how I start troubleshooting this sudden loss of power problem?

As always any help would be greatly appreciated!

[johnmart]

Hi Neo,
I am not a great technician, but my impression is that it is hardware at fault.
I would first open the box & clean it out well. Remove peripheral cards one-by-one & clean contacts with a soft eraser. Vacuum out the dust, be sure cooling fans are operating & vents are clear. Reseat ide cables. If you can, renew your cpu thermal paste. Be sure the cpu fan is running & the heat-sink is clear of dust.
I would also suspect ram chips. You can test them by removing one & testing.
If you at one time overclocked your cpu for stabiity, that could be a source of instability now & for sure produces extra heat. But I have no personal experience with that.
There are real technicians around here who can be of more help than this, but it can give you something to start on 'til real help arrives.  

[Crow]

Overclocked processors tend to overheat so the maintenance suggested by johnmart should be your first option.

[Archie]

Uhh ohh ... cross your fingers it ain't a failing power supply. But I ain't a technician.

[johnmart]

Good point. Neo, also check that the fan on your power supply is running. Should be able to feel hot air coming out.

[Ɗα√ϵς§]

I had a situation where the computer would mysteriously switch off. Cleaned up the insides, everything! Could see nothing wrong, but it turned out to be a overheating processor caused by a broken lug on the bakelite shroud that the heatsink clips on to. As it was the lower one, the heatsink appeared to be in place, and when it was cold, the heat-transfer paste held it to the processor. As it warmed up, it became less sticky and the heatsink moved slowly away. When off, the weight of the heatsink, without the spinning fan, meant that it fell back into place and stuck as the temperature cooled.

Of course I couldn't replace that little piece of plastic held on with two screws and I had to buy a new motherboard!!

[kjpetrie]

Silly question, but do the lights stay on when this happens? No, seriously, I had a problem once every six months or so with my first computer where it would suddenly reboot for no apparent reason. Then my second computer would sometimes just go off and I had to restart it manually. It only happened occasionally, and it was five years before it happened when I was using the computer at night...

The lights went out for a second, and the computer went dead. Nothing wrong with either machine, but they can't work without continuous power. Of course laptops are immune because they have an inbuilt UPS in the form of a battery, but if it's a desktop (and I suspect it is if you're overclocking it) then it is vulnerable to brief flickers in the lights.

Overclocking could also be the cause. Your computer processes something between 48,000,000,000 and 160,000,000,000 pulses every second, and if one of these is misread it will change an instruction and cause a crash. There has to be a huge safety margin to ensure every pulse is read reliably, and overclocking is basically reducing this safety margin and hoping to get away with it. Mostly you will, but only one pulse has to be misread, and even it's only one in every few trillions, the computer will crash within minutes.

[T6]

possible reasons for this to happen

1. memory modules not properly inserted or dirty, clean slots and ram, then re-seat modules

2. psu with voltage problems, verify bios for voltage values

3. mainboard failing, unplug everything there and check that nothing is damaged, burned, smells or looks like a reason, this mainboard could have electrolytic capacitors, see if any is inflated ro releasing liquids

4. video card not properly inserted or with dust, remove, clean and re-seat it on the slot

5. cpu and system temperature, after the restart event check bios to see temperature values

6. hard disk, can you run a surface test or a any other tool to discard hard disk errors?

"back then this was bleeding edge stuff and I had to overclock it to get it to run stable - I know it sounds weird but it's true"

i have heard this situation before, mainboard unstable or psu unstable, problems with voltages or capacitors

yes, it is possible that the cpu or mainbard finally are giving up

[johnmart]

See Neo, I told you the brain brigade would show up!
    

[Crow]

See Neo, I told you the brain brigade would show up!
    

Neo has not posted, probably broke the computer trying some of the answers 

[T6]

yes, use the wrong tool usually brings more problems than solutions and you end being creative

[Crow]

yes, use the wrong tool usually brings more problems than solutions and you end being creative

Unfortunately latest computers has the metal very tiny, I converted a 286 and made my own   , is somewhere in the patio