Computer randomly turns itself off

The dirty fan issue is very common and your cpu will shut down and save itself from burning up.
I had a customer bring in a pc, it wouldnt start. I looked at the power supply and it was caked. I opened the case and the whole complete heatsink on the cpu was totally full, same with the fan. It wasnt ordinary dust. Ordinary dust is grey. This was white and i knew what it was right away. I called my customer and said, did you drywall your basement. You can guess he said ya, how do you know? His computer told me the whole story. I cleaned it all up and away it went, good as new. One pc totally caked and choked up with drywall dust!
Still, even a very dirty cpu fan and heatsink can cause the same problem.
Same with a cpu fan that is going bad, it runs too slow and causes the cpu to shut down to save itself from burning up.
A tip for noisy fans. Dont just oil them, oil burns up too fast. Instead, go to the auto store and get a small tube of powdered graphite. Take the label off the fan, put some powdered graphite in the hole and then just a tiny bit of oil, then tape the label back on with a tiny bit of duct tape. All will be well with that fan for a long long time as long as you get to it before the bearings are shot! Trust me, i have been repairing fans a long time, works like a charm. Never use just oil. Thats why the noise comes back in a month, the oil dries up or leaks out but graphite powder doesnt! Never! Its too sticky.

Hi, I have a Philips ls2400 hundred and I have the same problem being that when I am watching videos or running multiple tasks my pc randomly shuts off without any warning. I first thought it was my ram and uprgaded it to 2 gb. Then i checked and found that my fan on my graphics card was burntout. I replaced it with nvidia 8400gs 512mb heatsink one not a fan and it worked ok for a week (maybe less). The problem has returned, so I installed Speed fan and these are the temps.

Motherboard: 50
CPU: 49
Hardrive:42
Graphics Card: 60-74max( Highest Ive seen it go)
Is the cooling on the graphics card or could there be some other inherent fault in the pc

I dont know a heck of a lot about temps on graphic cards as im not a gamer, so someone else can answer that. On the other hand, you could probably google the answer to that one. Seems that the cpu is ok, however, taking the heatsink\fan assembly off the cpu and cleaning it thoroughly is always the first place to start when not sure.
If you search here, using the word "graphite" you should find my thread about using graphite for fans, this goes for the cpu fan and often the vid card fan. If you have a fan that is noisy then graphite would likely be the cure. Not only does graphite cure noisy fans but it increases the output of the fan.
Try the cleaning process first and see how that goes. Or perhaps start with the video card. If you can get to the fan easily then try graphite powder and a bit of oil or replace the fan.

those tempts. are all hot at idle if u were gaming while they were recorded then they are fine. more air circulating in the case would help. for max tempt. the Graphics card is fine, and I say that and u did not tell us what card u have.

Graphics Card

I started with a ati x700 and then I upgraded to a Nvidia 8400gs 512mb. The ati had a fan which had stopped working and i replaced it with the 8400gs which has a heatsink

sup guy my buddies computer is doing the same thing, it was running real slow and would turn off after a couple min i tried running a virus scan in safe mode and turned off before it could finish so we just reformated it. still the same prob after about 20 min of just sitting there its would turn off the fans a clean and running good dont know what if could be.

First off, start with cleaning the heatsink\fan on your cpu and air-blowing the dust out of your power supply and other fans and all the dust inside the case, dust on the memory sticks and on the motherboard. Check all connections to make sure they are all good and tight.

If you should happen to have a power supply tester now is the time to check your power supply. One bad line can cause these problems even though the power supply still boots the computer it can be bad. Everyone should have a ps tester, they are cheap to buy and easy to use too.

You may have to reformat the hard drive and re-install your os.

Take the ram out, air-blast where the ram sits into the mobo or at least blow the dust out. Clean the gold fingers on your ram with soft cloth..
.
You can d\load free version of everest and other progs that will tell you the fan speeds and the power supply voltage readings and other readings.
If you can borrow a ps and temporarily install it on your pc that might tell you what is wrong.
Finally, take the side off the case and have a house fan blowing on high right on the cpu and see if that helps.
Go to my computer\advanced\startup and recovery\settings and take the check mark out of "automatically restart."
Check the video card fan to make sure its clean and running.

Re-set the motherboard by unplugging the computer from the wall and holding in the power button for a minute.
Note that these items are not in order.