Computer not powering up

  BLH 19:29 08 Oct 2003
Locked

When I press the power button on my computer nothing happens no power no lights on the motherboard or keyboard? it's completely dead. the 300w P/S is OK. could it be a M/Board or CPU failure. Advice please, thankyou.

  BarryKeith 19:42 08 Oct 2003

How do you know the PSU is OK? It could as easily be the PSU as the Mobo or CPU. It could also be a faulty drive that stops everything else working.

  Ben0012 19:48 08 Oct 2003

Disconnect all peripherals except monitor, keyboard, mouse. Then check output voltages from PSU. If OK then check voltages at end of supply lines to computer components. Remember a faulty component (eg floppy) could draw too much and corrupt the supply voltages to other parts.

  BLH 20:10 08 Oct 2003

I know the PSU is OK because my son tested it on his machine. I thought when you switched the power on the PSU a light flashed on the M/B and the num & capt locks flashed on the key board I get nothing?? which I thought was a sign of no power passing through the M/B. I'm obviously mistaken. thanks

  Gongoozler 20:20 08 Oct 2003

With an ATX system, which is almost any system made in the last 5 years or so, when you press the power switch you make a connection via the motherboard to the power supply that signals the supply to switch on. Failure to switch on could therefore be due to the switch, the switch connector on the motherboard, the motherboard, the ATX power connector on the motherboard, the power supply itself or the mains cable to the power supply. There is not usually a light on the motherboard itself. Without a test meter and some knowledge of using one to check continuity it is difficult to determine which component is at fault. You should first check the obvious things like the mains to the power supply and the motherboard connectors.

  woodchip 20:50 08 Oct 2003

It may be a faulty on button it's only a switch with two wires to it, so to try it you could use two bits of wire like if you was starting a car with no key just have a look for the small plug covers two pins normally bottom right corner of motherboard with PW for power on it just bridge these pins to try to see if it will fire up

  woodchip 20:51 08 Oct 2003

It may be a faulty on button it's only a switch with two wires to it, so to try it you could use two bits of wire like if you was starting a car with no key just have a look for the small plug covers two pins normally bottom right corner of motherboard with PW for power on it just bridge these pins to try to see if it will fire up

PS you cannot try a PSU for volts without a load on it, as it is a switching PSU in other word it only works when a load is put on it

  BarryKeith 20:58 08 Oct 2003

You neglected to explain what a load is! It may be worth a description.

  BLH 21:00 08 Oct 2003

Thank you all for you advice I'll give it a try,

  woodchip 21:01 08 Oct 2003

I.E the motherboard connected, and you test the psu at the back of the PSU plug on the motherboard while it's on. you obviously need the pin configuration and volts for such

  woodchip 21:02 08 Oct 2003

PS will that do

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