T42 failed to boot.

[ahhha]

My T42 reports an error:
...
Video BIOS shadowed
UMB upper Limit segment address: DC00
Mouse initialized
...

With only the light `power on` turned on, it stalled.
But I can enter BIOS utility by press F1, and I can not find my IDE0 hdd from Startup.

So I replaced it with a new IDE hard disk, now the lights for `power on` and `Drive in use` are on, but it still stalls.

Sometimes the new IDE0 hdd can be found from BIOS utility, sometimes can not.

It can boot up from a USB HDD, if the IDE hdd is removed from the machine.
But if the IDE hdd is plugged in, the machine stalls after the error message, with the lights for `power on` and `Drive in use` on.


I found thread at http://forum.thinkpads.com/viewtopic.php?f=2&t=43512, which says it may caused by a bad DIMM module or a bad system board.

But if my T42 is having a bad DIMM module or a bad system board, can it boot up from USB HDD?

[massits]

try with disinstalling and replace the ram modules, one for time

[RealBlackStuff]

Your problem is most likely a loose Southbridge chip (big Intel chip under the wifi-card).
Remove pamrest and wifi card.
Then put some pressure on (try different spots) that chip and try to start.
If it now works, you will need the Southbridge reballed, or a new motherboard.

[ahhha]

@massits, @RealBlackStuff

Thank you for your suggestions.

But it does not work. I tried both reinstalling ram modules and pushing on the southbridge chip.

Maybe the module to communicate with IDE interface has been completely dead, now I can not find the IDE HDD from BIOS anymore.

[massits]

you are the welcome

turn on the laptop, IBM Access, f1 go into bios and leave the laptop alone, after some munites, touch to try if the southbridge warm/ hot or not