Troubleshooting a suicidal T43p

[ajkula66]

The patient is a nicely-spec'd 15" T43p (2668-Q1U) that I sold to its present owner in 2008. Motherboard has been replaced by EzServ less than two years ago.

Latest stock BIOS and EC, factory configuration apart from a RAM upgrade.

The machine boots into XP, and within 10 seconds the CPU temperature shoots up from 35-40 degrees C to over 95 (according to TPFC) causing a shutdown. The same behaviour is present with no hard drive installed - you can get into BIOS and after 25 secs it goes out with the fan screaming. It makes no difference whether the machine is running on battery, adapter with no battery installed or both.

What I've tried so far:

- Swapped CPU and fan with known good units.
- Disconnected and/or physically removed: palmrest with FPR, wireless and BT cards, media drive.
- Swapped battery and AC adapter.
- Tried a different keyboard.
- Swapped RAM with know good sticks in all possible configurations.

I'm getting nowhere. Fast.

Any thoughts and/or suggestions are welcome. I'm fairly certain that I'm facing a planar swap here, but would love to understand what's wrong...

[dr_st]

Sounds like a faulty sensor to me. Even running with no fan, a crappy heatsink and no thermal paste I cannot see this CPU shoot up to 95C while idle.

[rkawakami]

My guess would be that one (or more) of the voltage supplies is out of whack. It's that or it's being overclocked. Those are the two main reasons why the CPU would consume excessive power.

Put together a liquid pump, a heat exchanger and a tank. Fill it with a couple of gallons of Fluorinert. Submerge the T43p in the solution, seal up the system and enjoy a cooler running T43p .

[ajkula66]

Well, the mystery has been solved, after quite some head banging...

Bad CPU + defective RAM slot under the keyboard.

It turned out that my "tested good" spare CPU was not good anymore... ...for whatever reason.

The machine started booting normally - then froze dead at XP login screen - when I installed the CPU and fan from my own T43p.

Pulled out the DIMM from under the keyboard and it's been purring ever since.

Not a bad stick of RAM since it passed all the tests when inserted in the other slot...

The machine currently runs - quite well I might add - with a single 2GB DIMM and a 1.86 (PM 750) CPU which is all I could spare at the moment...

Back to the Marketplace to try and locate a reasonably priced PM 780...

[dr_st]

I wonder if the RAM slot may be repaired. Reagle mentioned resoldering them on X3x's... But not every failure may be related to solder...

[ajkula66]

The way I'm looking at it, if he's going to spring out the $$$ for a replacement board or a proper repair of this one, he may as well get a SATA-modded planar...and enjoy that T43p for a few more years.

I have tried applying pressure of various sorts to the problematic slot and got nowhere so I'm uncertain whether it could be repaired...but after working on this machine, I honestly don't think I know anything anymore...