Motherboard light does not come on, harddrive LED is on, fans not working

[lynnaekae]

Fans went nuts yesterday and the CPU was throwing a lot of heat. After I cracked the case and cooled it down, on reboot there is power to the harddrive only - no motherboard LED or fan movement. I have taken everything apart, reseated all, and rebooted several times with no luck. Dead motherboard?

 

[hpdeskjet]

What are your system specifications? Sounds like either the motherboard or PSU died.

 

[lynnaekae]

It's an IBM ThinkCentre P4...really not much to it and is mostly used to run external harddrives.

 

[hpdeskjet]

It sounds like a piece of hardware died. Probably the PSU or mobo. How old is the system?

 

[lynnaekae]

Only 2 years old. Always ran pretty warm even though it has dual SuperRed fans by the processor. Problem with the IBM housing is that there aren't any vents for the heat to escape. I had the fans running for a few seconds and actually had the mobo LED light up while they were running. But then they kicked out and everything but the harddrive shut down again.

Is there any way I can test the psu or mobo independently?

 

[hpdeskjet]

For the PSU, you can paperclip test the PSU to see if it works. If it passes this test, it can still cause problems later though so the best way is probably to get a known working quality PSU from a friend or something and test it on your system.

Here is a link to the paperclip test:

http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

The paperclip test is somewhere after step 23. There is a youtube video that will guide you through the process. Try to be careful though since it is possible that you can shock yourself.

For the mobo, I suppose you can breadboard the system to check the mobo or test all your components on a similar mobo, though the second option might seem a bit more difficult in your case.

Here is a link to the breadboarding:

http://www.tomshardware.com/forum/262730-31-breadboarding

I would probably paperclip test the PSU first since I think it may be the culprit.

Edit: Can you also check the mobo for bad capacitors?

 

[jsc]

How do you know that you have power to the hard drive?

If you have any sign of power to the system, the paperclip test will not tell you much except that the aux power supply works and the 12 volt circuits provide a minimum amount of power to the 12 volt outputs. At any rate, this is a safe check. The green wire is a conrtol input to the PSU and when it is open there's only 5 volt on it. When it is shorted to ground, only about 2 - 3 ma. flows through it.

 

[lynnaekae]

The harddrive is the only thing that I can hear (and feel) running. So I'm assuming its got power.

 

[lynnaekae]

Ok, thanks for the info. I did notice that the PSU has both LEDs working but no fan movement...not sure what that's all about.

The capacitators all look straight and undamaged. No obvious heat damage to anything.