No boot, no beep

[Nuclear Powered]

I have a friend's computer which suddenly stopped booting. I took the motherboard out and replaced it and all the cards (video and CD-ROM I/O) and memory with a spare one I had lying around. Still no go, nothing, no beeps, no video, nada. Once, when trying to power it up I actually got into the BIOS for a moment, but next power up nothing. I replaced the power supply and tried again with the same results. Any combination of motherboards and cards provides no response.

I've tried with memory (both SIMM and DIMM) in all combinations and without. I still get nothing. I've even tried different monitors. Any ideas of where to proceed? I don't have another case or I'd even try that.

[BigBlue66]

Sounds like a power switch problem to me. There is a way to short a couple of pins to bypass the switch, but I don't remember all the details.

Hang tight for some more replies.

[Budfred]

I believe you just briefly touch the same 2 pins that the main power switch plugs into on the motherboard with a screw driver (being sure that you are insulated) at the same time. The contact should be very brief to work like the actual switch.

[Whyzman]

On most PSUs I've worked with the key is jumping the "Green" wire to ground.

http://www.pcpowerandcooling.com/support/ATX_troubleshoot.htm

This bypasses the momentary power switch and should turn the lights on! ;)

If you have any questions...I would direct you to the manufacturer's site of the individual power supplies where you'd want to look at the schematics. Since there's an accepted 20 Pin connector format though, they should be pretty much the same.

[Whyzman]

Testing:

You can test a ATX power supply without a motherboard, I do it all the time when troubleshooting. I am experienced with electronics ... and if you are not DO NOT TRY THIS.


*** MAKE SURE THE POWER SUPPLY IS UNPLUGGED FIRST ***

Simply Jumper Pin 14 ( which is the green wire) to any of the ground pins which are 3,5,7,13,15,16,17 ( all which have a black wire). I use a paperclip to do so, just stick the paperclip into the connector like you would be pluging it into the motherboard.

[Fruss Tray Ted]

Watch those numbers though... Make sure they are black and green.

There was a thread back a ways that mjc was part of and he noted that some propietary companies have customized the plugs so the colors aren't always in the order Whyzman stated.

Just a heads up...

[Whyzman]

Good point Fruss...

Point being, find the documentation for your particular Power Supply/Motherboard first! :)

[Budfred]

You guys are talking about testing the power supply, but the original thought was that the case power switch is bad. Are you thinking the power supply may be the problem???:confused: If so, note that he already tried a different power supply with no joy...

[Whyzman]

No, wasn't trying to get the PSU tested...just fired up by bypassing the momentary switch...

Sort of did sound like a test though...:p

[Fruss Tray Ted]

I had a pc that the switch was fine but the circuit it plugged into to command the PSU to come on wasn't working. The workaround was to short the 2 leads that powers up the PSU and I was able to use the pc that way. But that also bypassed the safety auto-shutdown features too.

So no, it is to see if the fans and such will power up to narrow down where the fault is.