Computer will not turn on

[matt]

Hello all,

My roommates computer will not turn on.  He can not remember the last thing he was doing on it or when he turned it off last, but now it will not turn on.

I do not have another PSU to check but their is a LED on the motherboard that indicates when the power is connect and it is light up.  Still, when I push the power switch nothing happens.  I have taken a switch out of an old computer and tried that, which doesn't work either.

It is a custom built PC:

COOLMAX V-400 ATX v2.01 400W Power Supply
AMD Athlon 64 FX-55 ClawHammer 2.6GHz Socket 939 Processor
EVGA 123-K8-NF47-AX 939 NVIDIA nForce4 SLI X16 ATX AMD Motherboard
TwinMOS 1GB 184-Pin DDR SDRAM DDR 400 (PC 3200) Desktop Memory
GECUBE GC-HM13GE2-D3 Radeon X1300 512MB(256MB on Board) 64-bit GDDR2 PCI Express x16 Video Card
Windows XP

I have no idea what could be going on here.  Maybe burnt out mobo or CPU?  Any ideas??

Thanks!!

[patio]

That tiny LED on the MBoard is no indication of the health of the PSU...i would borrow another PSU of the same or greater wattage and start from there...

[matt]

I have tested the PSU by shorting pins 14 & 15 and the power supply turns on and its fan spins.  Is there a way to test CPU / motherboard without swapping the CPU?

[pudco]

I don't think it's hte processor becuase I've turned on a computer without a processor in it before. and it still starts.. just no display or anything, but the fans and the drives all came on (yes atx, not an at).  The stupid stuff I did when I was younger messing wtih pc's haha...  but yeah I don't think it's cpu.  Maybe bad button or wires on the button, or else perhaps it got a surge and the board's fried.  Newer power supplies don't turn off 100% like the old kind did, therfore electricity is still flowing through it all the time..  Surge protector or not it could still happen trust me.  My mom's got hit by lightning once and the surge protector was all over the floor when I found it after that. Her computer was fine becuase it was the old kind with a switched button not a soft type button.  Surge protectors can help surges but still they don't stand a chance against lightning.  So that's a possibility that it could have been hit by lightning.. Lightning can cause strange things, trust me I know that, I lose something every year to lightning strikes, and I myself have almost been hit twice...

[matt]

I hope it is not the CPU but fear it might the motherboard....

I have gone through several steps:

When shorting pins 14 & 15 on the power supply cable, the power supply turns on and its fan spins along with the hard drive plugged into it and a case fan.

I have also tried removing the power switch connector and manual shorted those pins to turn it on, but still no success.

The motherboard has a on-board POST system, that that does not light up nor can i see any indication of power flowing to the board expect for the LED

I have also cleared the CMOS using the jumpers and also tried removing the CMOS battery for a few min then replacing it.

I have removed and reseated the video card and ram.

I have also removed and reseated the motherboard to check for shorts with the case, and also checked for any heat damage and didnt see any.



Any other ideas or suggestions on how to test the motherboard?

[patio]

That tiny LED on the MBoard is no indication of the health of the PSU...i would borrow another PSU of the same or greater wattage and start from there...

What you have done so far is still no indication of the health of the PSU.

[pudco]

Also what I said about the lightning earlier could be true for the psu as well not just the board.. Computer power supplies are switching power supplies meaning they put out more than one voltage at a time, which you probably already know this if you're going around shorting out pins, lol.  It's possible that one or more of the voltage channels (I don't know how else ot word that) coming from the power supply is bad, possibly not even putting out any voltage.  Or, it is putting put the voltage but when a load is put on it is drops to 0 becuase something happened to the power supply.. Just try what everyone here mentioned, get another power supply and see if that fixes it, if not I am putting money on the board. Perhaps chipset or BIOS chip

Jay

[patio]

Also what I said about the lightning earlier could be true for the psu as well not just the board.. Computer power supplies are switching power supplies meaning they put out more than one voltage at a time, which you probably already know this if you're going around shorting out pins, lol.  It's possible that one or more of the voltage channels (I don't know how else ot word that) coming from the power supply is bad, possibly not even putting out any voltage.  Or, it is putting put the voltage but when a load is put on it is drops to 0 becuase something happened to the power supply.. Just try what everyone here mentioned, get another power supply and see if that fixes it, if not I am putting money on the board. Perhaps chipset or BIOS chip

Jay

Who the heck is writing these scenarios for you ? ?

[matt]

What you have done so far is still no indication of the health of the PSU.

You were correct, I was finally able to borrow another PSU and it powered on.  I feel foolish 

Thanks all!

[patio]

No reason to feel foolish Matt...it's a learning process.
Just make sure when you get a replacement don't buy a $20.00 special or you will soon be in the same boat.
And if you are planning an upgrade somewhere down the road buy for the future.