Computer won't boot

[kevin.grossman]

I'm having problem getting an older pentium 4 computer to boot. The
power switch doesn't do a thing except light up the power LED on the
case. The power supply has a test switch and when I turn that on, the
CD Rom, Hard drive and fans come on, but I don't hear the "beep"
indicating that the computer is trying to boot. There is a green power
LED on the motherboard that's lit though.

I'm guessing the problem is either with the motherboard, CPU or with
the power switch from the case. However, I don't know how to
troubleshoot these without having a spare of each. Any suggestions?

Is there a way to get the motherboard to power on without using the
power switch on the case?

Thanks,
Kevin

 

[Jan Alter]

Hi,
It is dubious that it's the power switch on the case if you're getting
power to those peripherals. All the power switch does is create a momentary
short and then allow the PS to send the current. It however could still be
the PS or it might be the Heat Sink Fan as well as the mb or cpu. Try
reseating the graphics card first, and try it again. That additionally would
be a reason for the mb not to post if none were sensed.

 

[don]

Reseat the Mem and try. (unplug the PS first) if this does not help then.

One of the wires connected to the motherboard is a power good feedback.
although the power may be getting to the MB it may be out of spec and
therefor not feeding back on this wire.

This may be occuring because of the PS itself, or because of some componant
that has failed.
Try disconnecting all connectors to the periferals (HD, CD, Floppy, etc.) If
this allows the machine to boot then shutdown connect the periferals one at
a time and try booting to single out the bad device, if this doesn't help
then backprobe the connectors to check for proper voltage levels from the
PS. If none of this works then it is most likely a voltage regulator on the
MB and replacement of the MB may be your most cost effective solution.

Occasionaly a bad led on the case can cause a short, but is not very common.

 

[Mike Walsh]

Remove all expansion cards, including video. Remove memory. Unplug all disk drives. The only thing left should be the power supply, motherboard, and CPU. When you turn on the power you should get a beep for no memory. If there is no beep check the power supply voltages with a good voltmeter.

 

[Draco]

Well if you supect that it is the switch you can take flat tip screw driver
and touch the to prongs on the mother board where the power switch can
connect to. You can also remove all the conections and just have the power
switch conected to the mother board and see if it boots up. It is kinda rare
but i have seen it on one pc where when everything is hooked up like it
suppost to be it still does not boot up but powers on.

 

[don]

You mean a continuous beep right?

one beep means all good.

Remove all expansion cards, including video. Remove memory. Unplug all

disk drives. The only thing left should be the power supply, motherboard,
and CPU. When you turn on the power you should get a beep for no memory. If
there is no beep check the power supply voltages with a good voltmeter.

 

[Mike Walsh]

With most BIOSs one beep is good. No memory detected will give some other indication e.g. three beeps (possibly repeated every few seconds. No beeps usually indicates the BIOS is not running. A continuous tone would also indicate a problem with the BIOS or some other problem with the motherboard.

 

[Xyvik]

I'm also having the same problem on my machine. However, instead o
the fans turning on and off, they simply keep going, but there is n
POST. Tried removing the memory to at least get a beep, but nothin
happened. BIOS problem