Heat damage? What's your best guess between MB and CPU?

[Barny]

Hi All, I'm trying to fix a neighbors PC that I'm pretty sure has heat damage.

What's really really strange is the fact that it won't boot at all when it is cool. Only after the BIOS says it has heated up to over 110 degrees will it actually boot. Once it actually does boot, it'll run until it gets powered off and is allowed to cool again!!!!! I can restart it at will as long as I don't let it cool down.

He's kept this thing in one of those desks with a small cubby hole for a PC; maybe 1 or 2'' of clearance for air movement - not good. When I checked it out I found no case fans and the power supply fan was not spinning. The only cooling was coming from the CPU fan. I opened up the power supply to see if I could lubricate the bearing on the fan or just replace the fan in it. I found melted wires and a lot of darkened areas around components.
We replaced the Power Supply and I added a case fan.

While under 110 degrees:
This thing boots off of diskette 'ghost' but locks up about 20% into the drive integrity check.
Then unplugged the Hard drive and tried to boot Knoppix linux off CD - also froze.
Got a copy of the IBM Drive Fitness Test (DFT) diskette. This booted and tested the hard drive without error.
I had done all of this with no adapters. Basically running minimum config.
It has 2 DIMMs in it. I tried booting with just one then the other - no change.

So, It seems I'm down to either a cooked CPU or cooked Motherboard. Or should I say a frozen CPU or frozen Motherboard.

Now, I know some of you might say just let it heat up and leave it on. This will likely be the short term solution. I'm prepping for the longer term solution for when it finally craps out completely, if it does.

Which is most likely the problem in your experience?

 

[DimZiE]

my bet it's the motherboard.

but just before you buy a new board, you might want to try testing all the components on another system, then you could determine which part caused the problem..

 

[Barny]

After thinking about this over the last day I agree with DimZie and am leaning toward the MB.
The only conclusion I can come to is that there is a cracked land pattern somewhere on the board. This might explain why it won't boot when cold but runs flawelessly after it heats up which could cause the land pattern to expand and close.

Everything has been eliminated except the CPU and MB and I don't have another machine I can swap with.

This being an older system, has anyone had any luck locating replacement MBs for 900 Mhz AMD Thunderbirds? I'm trying to save my neighbor from having to purchase a MB, CPU and Memory in order to resolve this and this system is quite adequate for his use.

 

[montag451]

Thing is, that if you get a new mobo, this might mean a new install as well..........

I would also think that most 462 pin mobos [if that is what your cpu is], would be able to support that cpu.
Might be able to get a cheapie from a shop wanting to get rid of old stock, or Ebay.