pc turns itself off.

Philc · 29 Jun 2006 at 11:44

Hi my PC downstairs seems to be lately just switching itself off. It was just happening when playing bf2 but now its does it when just pasting a picture of something. When it shuts itself off the front green LED blinks every second and the computer wont turn back on, unless switched off at the back.

spec
AMD 3200+ 754 - zalman 90cm cooler
MSI neo
geforce fx 5950

i figured it could be overheating but when i turned it back on and checked the BIOS it said 50c which doesnt bad enougth to cause a shut down. Any ideas?

Nami · 29 Jun 2006 at 12:12

If thermal throttling is turned on (BIOS setting) then it could be temperature related. When are you say it is 50 degrees, is that when you first turn the PC back on again? Or when the PC is idling? The temperature of PC components changes almost instantly in response to load, so 2 mins after your PC turned itself off you might be seeing 50 degrees, but when it was in game it could have been way higher.

In all honesty tho, it sounds like a potential PSU problem. I'd suggest reading the sticky threads in this forum and trying the suggestions there (e.g. CMOS reset).

Try a different power cable to eliminate that early on - there is nothing more frustrating than spending hours changing components only to find that it was a cable that takes 30 seconds to change!

Philc · 29 Jun 2006 at 12:42

Yea thats wierd coz i had a feeling it was to do with the power supply. Ill try and change the lead. If it is the lead though how can the lead make it do that?

kona ryan · 29 Jun 2006 at 12:51

Nami said:
Try a different power cable to eliminate that early on - there is nothing more frustrating than spending hours changing components only to find that it was a cable that takes 30 seconds to change!

A kettle lead would not cause that, imo it is almost certainly the powersupply, check the fan in it, the same happened to me once and it turns out the fan had failed which was causing the thermal cutout in the psu to blow.

Ryan

Nami · 29 Jun 2006 at 13:49

I just think that if the lead isn't making a proper contact to the PSU then it may cause problems. Considering it's a 30 second job, I strongly believe that you MUST try this first, even if the likelihood of it being the lead is low. Imagine how stupid you would feel if you spent days looking for the problem and then it turned out to be the lead that you never checked

As I said in my original post tho, it does sound like a PSU problem. My advice is still to try the lead first and eliminate it from your enquiries. Then perhaps try downloading some diagnostics software so that you can look at the voltages on the various power rails. Then try loading the CPU - do the voltages change significantly?

I assume that the green LED you refer to is the power LED on the case. If this is blinking when the PC switches itself off, that suggests to me that the motherboard knows that there is some sort of problem and has turned the PC off to prevent any damage. It may have done this due to overheating or power deficiency, perhaps.

Those are my thoughts, I'd try playing about a bit and come back to us with the results.

t31os · 29 Jun 2006 at 14:23

Leds on the case indicate power or hdd activity, can't ever remember them relating to errors with the hardware, don't know how you came up with that.

The power LED will flash when the pc is powered up or down naturally, and the HDD led is always going to flash when booting or shutting down because the HDD is being read or written to.

Unplug all the devices the pc doesnt need, ie, cd drive, extra hard drives, usb devices like webcams. Basicly take out anything that isnt required to boot into and use windows. If your problems disappear you can be sure its either one of the devices you've removed, one of the cables to one of them devices, or most likely the PSU.

Philc · 29 Jun 2006 at 17:50

t31os said:
Leds on the case indicate power or hdd activity, can't ever remember them relating to errors with the hardware, don't know how you came up with that.

If the computer has fully turned itself off and the power led is blinking how can that have anything to do with hdd drive activity, i have to agree with the other guy i think its something that the motherboard does to say somethink.

t31os · 29 Jun 2006 at 18:06

I didnt say the blinking was the HDD, re-read my post.

Sorry i did miss the part he said it was blinking when its shut down, which to me would indicate the PC still is recieving power when its not booted, in which case i would think its incorrect wiring or a short somewhere.

tipsy · 30 Jun 2006 at 05:21

I had this with a pc I bought from local shop (3 or so years ago), couldnt be bothered to build it myself & gave them the spec I wanted U know the usual ram, mainboad, case, psu (sorry 4got 2 say it was a part build).

anyway The PSU was a 400w qtec lasty thing much to my disgust but it was functional for my second pc. After about 6 months the pc would switch off whilst playing cs & toca race driver. Initially I put it down to overheating so I ran it with the side off but much to my dismay it continued. I checked the cpu, ram, unpluged drives (ran fine with dvd/dvdrw unplugged), suddenly I thought PSU & I replaced it with a 380w antec psu & it worked flawlessly & did till I sold it, mind a cheapo psu went into it when it was sold a sI still have the nice antec psu

Basically I will totally say it it the psu & 12v rails being low hence the switching off as this is doing the same as mine did, unplug your drives & try running it.

I hope this was sorta helpful as I'm going off experience

Philc · 30 Jun 2006 at 13:39

thanks fur the replys. The power supply is a 480w thermaltake one. Cost about 70 squid. Its been working for ages now. Today i installed motherboard monitor and under the 3.3v header is was reading about 3.1, when i played BF2 it dropped to 2.7. All the other rails are ok. Can i perfectly good psu suddenly do this and what would cause it?