Computer will not start at all

[Zylstra]

I am working on a computer that will not start at all.
We've checked every cable, cleaned out the computer, checked all the connections, removed all devices, tested RAM, checked IDE connections.

Nothing is happening at all.

When powered on, the fans inside the computer begine to run, but nothing happens after that.

We have left the hard drive unplugged, and the CD ROM drive unplugged (as well as floppy drive) for now.

An intresting thing that happens is this:
When the hard drive is plugged in (power only, no IDE connection) the hard drive makes its usual startup sounds. When plugged in with IDE connection, it makes no sounds and appears to not be poweing on at all.

There are no post beeps.

This is a school computer and it does have antivirus and spyware and adware protection.

It has an AMD processor that (I think) runs a little over 1GHz.
It has over 256MB RAM
I cannot give exact specs

[mektek]

Is your Power Supply Unit (PSU) supplying the correct voltages. If it is not then it may not be giving out enough power to supply all the devices. You will need to check it with an electric meter http://www.computerhope.com/help/ps.htm

If the PSU proves to be healthy then you may be looking at a faulty motherboard but test the PSU first as this is the cheapest and easiest option to replace.

[street1 (RIP)]

Did someone remove a jumper from the motherboard,or are you
the only participant? :-?


SNAP! Wow!

[Zylstra]

Is your Power Supply Unit (PSU) supplying the correct voltages. If it is not then it may not be giving out enough power to supply all the devices. You will need to check it with an electric meter http://www.computerhope.com/help/ps.htm

If the PSU proves to be healthy then you may be looking at a faulty motherboard but test the PSU first as this is the cheapest and easiest option to replace.

Well, we just put in a new power supply. We are going to try one of the older ones today...

Street1 quote

Did someone remove a jumper from the motherboard,or are you
the only participant?  
 
 
SNAP! Wow!  

Jumper? From the mobo? Everythings plugged in right, though there is a sub power cable going into the motherboard we cant quite figure out. I belive its optional...
Its a four-wire cable thats along the bigger plug with who-knows-how-many wires...

[street1 (RIP)]

Do you have the 20pin cable then the additional P4 connector?

I think you need it plugged in for the pentium4 processor to function.

[Zylstra]

Do you have the 20pin cable then the additional P4 connector?

I think you need it plugged in for the pentium4 processor to function.

Ill check