TechSpot

Pc Switches Off

By Wondersheep
Jun 12, 2007
  1. Hello, I am new here but am hoping I can get some help.

    When I play a certain game (have done virus / spyware scan and pc is clean, game is system resource intenesive though.)at random times the PC will just switch off. (power light blinking on and off)

    I have to unplug it from the mains for about 5 seconds to stop the light.
    But if I just switch it back on, it starts to power up then after 2 seconds switches straight back off again.

    To get it to come back on completely I have to unplug the power from one of my Harddrives.

    Same happens if I just switch the pc off, I have to unplug one of the harddrives to be able to switch it back on.

    Now is this the HD failing, or is it fault with the PSU?

    Any help is much appreciated

    Thanks
    James
     
  2. Phantombadger

    Phantombadger TS Rookie Posts: 20

    You said you have to disconnect a HDD to get it to work. and that this only happens when you play a certain game. First off. check your PSU stats against your video Card. how much you vid card requires and how much your PSU puts out. not just wattage but Volts per rail.

    | Output | +3.3V | +5V | +12V1 | +12V2 | + 12V3 | +12V4 | -5V | -12V |5Vsb
    750W 24A 30A 18A 18A 18A 18A/22A - 0.5A 3.0A

    This is what mine looks like you should have something similar to it on your PSU or the Box your bought it in( if its not OEM or you still have the Box); Also you should be able to get this info from your PSU manufacturer. this info is very important, your video card needs so many amps on a rail, if it shares a rail then it will power done, but usually you will get a notice before it shuts it down letting you know there isnt enough power for the vid card. So I dont think its that but as it happens in Game make sure you Vid card is on its own Rail. I have 4 12V rails and I highlighted Rail 2 in Green.

    Second thing you can check is how many HDD's you have on a rail. check the net for limitation but usually its hard to overload a rail with HDD's alone on the provided Molex connections. usually 3 per rail. Faster drives, Raptors, use more power so be aware of these too.

    Third it may be an all around psu failure. check the power requirements you need Here
    This will give you an idea of what you need under load.

    Forth Check your CPU and PSU for Dust, possible overheating shutdown safety mechanism. If its caked with dust get a can of Air or compressor and blow it out. And make sure not to spin the fans as the bearings could be blown to death.
     
  3. Wondersheep

    Wondersheep TS Rookie Topic Starter

    Hello

    Thanks for the reply.
    Turned out it was only a 250W power supply and it finally died last Friday, so I guess it was a psu problem.

    So I got a new 480w PSU. Fitted it, with a new Radeon x1950 pro GFX card too.

    Switched it on, and I get no display (monitor just says no signal) so thought maybe fault with card. So put old one back in, still no display.

    so changed the Motherboard completely.
    Still, the same problem.
    No display at all, even from the onboard Vid card. monitor just will not display.(Even tried testing it on my tv throught the VGA socket, still nothing, could it be the actual Monitor Lead at fault?)
    So any suggestions what it could be?#

    Also the psu came with a 24 pin connector where the mobo is only 20 pin, but the plug has a notch at the 20 pin line so it sits in fine.
    Would that cause a problem?
     
  4. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,715   +397

    The 20/24pin won't cause any problems. Make sure that if your motherboard has a 4 pin (in a square configuration) plug anywhere on it that you have power plugged into that.

    Also it is entirely possible if you picked up a cheap 480W PSU that it is dead. Cheap power supplies have an incredibly high failure rate.
     
  5. Wondersheep

    Wondersheep TS Rookie Topic Starter

    Hi

    Yep it is all connected.
    Everything seems to power up, HDD, all fans. DVD drives. I just get no display whatsoever

    So could a cheap PSU still be the problem. It is a Dabs Value 480W power supply
    New Vid card wont display, old Vid card wont display, onboard vid card wont display.
     
  6. mopar man

    mopar man TechSpot Ambassador Posts: 1,379

    Most cheap PSUs tend to have a worse failure rate. Look for reviews of the Power supply.
     
  7. Wondersheep

    Wondersheep TS Rookie Topic Starter

    Yes I understand what is being said but if the PSU failed, would it still power up everything else, HHDs, Fans (even fan on GFX card) DVD drives (both of em) but stop a Vid Card even onboard Vid Card displaying.
     
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