This started happening this morning, I recall watching videos on YouTube. It shut down without warning, and I was not able to turn it back on-- the 'on' button was flashing yellow. I turned off the powerstrip and then was able to turn it back on. Though it shut down again soon afterwards.

I don't know how hot my video card is running, but it doesn't have any reason to be getting hot-- since I do not do anything intensive. Both video card and PSU are not more than a year old-- I put in new ram about 3-4 weeks ago.

It's happened 4 times today in total. I've run virus checks. The only thing I can say about its occurrence is that it has happened when I've had multiple tabs open on browsers.

Operating system is win xp. Any suggestions would be helpful.

There are a few reasons as to what could cause a PC to shutdown:

(1) a Trojan, if your antivirus is a paid version , regularly updated and reputable and it found nothing, then you can rule that out.

(2) a heat related issue, possibly the CPU is overheating or a failure in the Fan.

(3) a memory issue, which I would be moving towards as the culprit as you say you put in new RAM.

When your PC is running and you have a few tabs open, press Ctrl + Alt + Del to open up Task Manager, click the "Performance" tab and see what your "CPU usage" and "Memory usage" is ?

Could it be a ram issue if I have sufficient ram even without the newly installed ram?

In task manager, the spikes reach fairly high when I open up some new tabs, or my email program, but then other times they don't. I don't know how normal all of this is. Under physical memory it says, total: 3144700, available: 2611728, system cache: 551468

Those figures are excellent, you have well over half your memory in reserve. Why did you install new RAM ?

Have a look at the Fan that covers the CPU, does it need to be cleaned ?

What antivirus software did you scan with ?

Did you install any new software/hardware prior to this fault ?

I dusted not long ago. Did virus scan without system restore in safe mode both with avira and spysweeper and found nothing. Only thing I can tell you is that I was experimenting with proxies the night before, which I'm not experienced with. Only recent program I've installed is the browser SRWare Iron.

you could have a bios problem I had the same thing it would randomly shutoff and not turn on till power was interrupted and restored I put a new powersupply in it and no problem during a reboot try to write down the bios number and call the system manufactur and ask them about it cause I updated my bios and it worked

If that was me, I would have done something like system restore. Just an advice.

My opinion is that its over heating. Many devices not just computer have lights that display power. I have a DLP Projector and when I turn it off the light goes from green to yellow and blinks. I have to wait until it turns off before I turn it back on.

I would say it's overheating soemwhere therefore shutting itself down to cool off.

Dust off your motherboard especcially your heatsinks and fans.

Did this do this before you got that extra RAM stick.

He's got a point with the added performance your computers cooling system may not be able to compensate for the extra heat from the ram but it still sounds like a bios or powersupply problem

For BIOS updates you can visit the site of your manufacturer

Thanks fellas, but it stopped doing this. I ran quite a few virus checks, and even though they didn't seem to find anything, I haven't had this happen since. Maybe it can still happen, who knows.

That's good but be prepared for it to do it again you never know but glad to hear u fixed it

Speak of the devil, it happened the very day I made that post, and has been happening more frequently. Just this morning it shut down before I even logged on. It happens both in linux and xp so I figure it's hardware related.

It seems like it would either be the videocard or the PSU, is there a way to test either? The PSU is 500 watts, I've had it for maybe a year and half, same with the video card. I updated my BIOS a year ago as well.

Switch out the powersupply don't take it apart cause you could still have the warranty but do smell the powersupply if you smell burning or anything unusual then that's it as far as the video card goes it is highly unlikely that it is the culprit if anything it wouldn't show video at all if the powersupply don't work update your bios again let me know

Thanks. I have the PC on my desk now and all the fans I can see are running. Nothing becomes particularly hot, the video card is warm.

One thing I will add is that there seems to be a lot of static in my living area, there are small shocks all the time. Could there be any relation? In fact there was a small shock when I touched my video card just now, but nothing appears to have happened. It seems doubtful it is static because the shut downs happen with recurring circumstance, as in going to a particular website.

You say I should restart the BIOS, what would that do?

I wouldn't say it is the static I would try the powersupply because it is safer you could even use a powersupply from another desktop
If the powersupply doesn't work then go to your motherboards manufacturs's website and make a bios update disk(really simple)
And update it, before all of that do a scan with a program called malwarebytes antimalware(it's free) if not try the above starting with the powersupply

dude, I have the same problem. Ill explain mine, tell me if you get anything similar

it shuts down randomly as you say, sometimes ill be using the pc; internet, utorrent, itunes, msn. Then bam shuts down.

as you've said, I can't just press the on button. I have to switch it off at the back of the PC, turn off the power. Then turn all those back on again before starting it up again. It loads, and sometimes, before its finished loading the desktop shortcuts, it'll shut down again.
start up, does the same thing over and over. So I end up having to leave it off for a few hours before I can use is.

other times it'll start back up normally, but say I was reading an email when it last shut down, if I go back to that email, it'll shut down again. And again, and again.

other times, it'll shut down while I'm running a scheduled virus scan with AVG. I've got no viruses, some cookies in Firefox, and I used to have trojan threat, but it hasn't appeared for MONTHS...

anyone else got any insight as to why the PCs do this?

I've got an old custom made PC, 2 fans, 2gb ram, 3.14 processor, duo core its about 3 yrs old.

on another side note, I've got some bad earthing in my bedroom, like any exposed metal connected to the plug or any plug to the socket, then you'll get minor static.. I've had it since we moved into the house.. but the PC never used to randomly shut down before.

thank you

If you are using a shared computer, maybe someone has set a timer on it.