Computer resets itself

[KoolAidMan]

My computer has been running fine for almost two years now, but when I brought it home from school it has started to reset itself while running. It usually does it before it even gets booted, sometimes on POST, sometimes on the windows load screen, and somtimes it turns on and does it after its even booted. I set it up tuesday night and it did it three or four times while playing WoW. Wednesday I couldn't even get it to start. I played around with stuff, reconected everything and still nothing. I reset CMOS and it worked perfectly for 4-5 hours of playing WoW. Woke up the next morning and it wont work again. Try everything I tried yesterday and no good. It has to be either the PSU, CPU or Motherboard I think, because it'll do this when I'm in BIOS even with nothing but my cpu ram and video card connected, and it does it with either of my two video cards or with any combination of my 3 ram sticks.

I dont have any extra parts to try out while I'm at home to see if replacing the PSU helps or not.

Any help anyone can give me would be greatly appreciated.

 

[Smilin]

Yeah, a computer that is "cranky" about booting is often a sign of a bad PSU.

CPU problems typically manifest as spontaneous reboots or random BSODs.

A resistor, a paperclip, and a $19.95 multimeter from radio shack can tell you if your PSU is bad. Disconnect the PSU from everything and bridge the green wire to a ground (black) to activate the PSU. Put a 5v or 12v rail under load with the resistor then measure the voltage with the multimeter. You should be +/- 10% while under load. Keep in mind that testing without load won't be accurate and with some power supplies can damage them.

 

[KoolAidMan]

So are you saying it could be either, or would the reboots be happening once it boots up if it was the CPU? I may have to go get a multimeter to check this out I guess, it would probably be good to have.

 

[FlyingPenguin]

Could be a bad PSU or a bad mobo. Memory and CPU is possible but unlikely.

Check the mobo for bad capacitors. This is a common problem with 2 - 3 year old mobos and PSUs. Check the photos here for what to look for:
http://www.pcstats.com/articleview.cfm?articleID=195

Try uninstalling and re-installing the memory. Sometimes you get a bit of corrosion on the edge connectors over time. Reseating them should clean them. You can also lightly rub the contacts with a NEW CLEAN pencil eraser to get the thin patina of corrosion off them. Use static discharge precautions (wrist strap, etc) while working on the sticks.

Could be a card that's shorting the bus out. Try pulling all the cards except the vid card and swap the vid card out if you have a spare POS card lying around.

Check the CMOS battery with a digital meter, or just replace it (it's only $2). Some mobos get cranky when the CMOS voltage drops.

Everyone should have a spare PSU on the shelf anyway so I'd try swapping that out next.

Hope this helps...

 

[Smilin]

Originally posted by: KoolAidMan
So are you saying it could be either, or would the reboots be happening once it boots up if it was the CPU? I may have to go get a multimeter to check this out I guess, it would probably be good to have.

Booting can place a heavy load on your PSU. Fans and drive motors are winding up, and the CPU gets busy quick once post is complete. If the PSU isn't up to par, this is the time is is most likely to fail. If it were CPU, it would either fail to boot at the same place each time, or it would boot fine each time but then later have random problems.

It could be something other than your PSU, but some clues point to it. Again, it's pretty easy to be sure with a multimeter.

Be sure to use a resistor across whatever you are measuring. I think a 25ohm 10watt should work, but double check the 'net. This is from my memory and it's been a while since I had to test.