Dell Demension 8400 fails to POST

[jca2323]

Hi,

My dell demension 8400 now will no longer POST. It just stays steady amber and nothing else. No video output and no fan. This started one day after using it the fan just speed up far above what is the maximum speed.

The computer has done all of the following in the past six months.

Motherboard fails to POST.
Memory Test Fails.
System randomly and/or constantly reboots itself.
Fails to fully boot (or even install) Operating System.
System randomly and frequently freezes.
Random & frequent 'Blue Screens of Death'
BSoD or hard freeze under heavy drive activity
Resetting the system after a freeze and the system will not repost

This computer is old, but it is still valuable to me and the rest of my family. I didn't find out about motherboard capacitors until recently. I had suspected it was do to the internal battery or bad power supply but nothing. Although, the day before this happened I was warned with "System voltage low", but I don't believe the internal battery is the problem. I was wondering if the board is completely gone or is it able to be recapped. I will hopefully have some pictures up soon.

[Taxman]

Re: Dell Demension 8400 fails to POST

It's not clear from your post - have you actually changed the CMOS battery and / or tried another PSU?

[Taxman]

Re: Dell Demension 8400 fails to POST

PS - Do you know if the motherboard in your 8400 was manufactured between April 2003 and March 2004? If not you can most likely (not entirely though) rule out a motherboard failure from defective capacitors. Apparently...

[Taxman]

Re: Dell Demension 8400 fails to POST

I found numerous possible solutions (link below) from others who fixed the same problem. Overheating seems to be a very standard issue in this model but most of the successful fixes were other random adjustments, eg reseating the CPU, removing the CMOS jumper and even wiggling a fan.

If it is indeed a case of bad caps though, the likely culprits apparently are those behind the CPU and under the cooling fan.

Hope this helps.

http://www.tomshardware.co.uk/forum/...352_28_50.html

[jca2323]

Re: Dell Demension 8400 fails to POST

PS - Do you know if the motherboard in your 8400 was manufactured between April 2003 and March 2004? If not you can most likely (not entirely though) rule out a motherboard failure from defective capacitors. Apparently...

The computer was manufactured during 2004, let me get the month of manufacturing.

[Gariarto]

Re: Dell Demension 8400 fails to POST

What is the status of the rear "A B C D" lights ?

If the motherboard capacitors appear to be OK, try another known good PSU.

A couple of clear, close, well lit pictures of the motherboard with the CPU fan shroud removed will help us to help you.

[jca2323]

Re: Dell Demension 8400 fails to POST

I'm sorry for bringing this dead thread back to life, but I just got around to checking the inside of the computer. I think the caps are leaking as there is the blue substance that dried on them. Some are bulging. Amazingly, the motherboard doesn't appear to have suffered any physical damage. The caps didn't leak onto the board itself.

[cheapie]

Re: Dell Demension 8400 fails to POST

The blue is just ink from the factory, probably to help with installation. If the caps are in fact bulged, then that is almost certainly the problem.

[jca2323]

Re: Dell Demension 8400 fails to POST

The blue is just ink from the factory, probably to help with installation. If the caps are in fact bulged, then that is almost certainly the problem.

Yeah, some of the caps are bulging a bit. The PSU might need replacing to. I am sure that the cmos battety needs replacing, too.