Some t21 CPU questions

[synchromesh]

Hi everyone, this is my first post here. I'm a fan of Thinkpads and I currently own a T40, T20, T21 in the process of being fixed and T23 parts machine.

I have a t20 thinkpad with 750MHz CPU. It's a 2647-92U machine.

Recently I aquired a dead t21 to fix. Someone spilled beer on it. The motherboard seems to be dead. I took out the CPU (800MHz, SL4GT) and installed into my working T20. It wouldn't boot up.

I have a few questions:

1. Does the fact that T20 refused to power up with SL4GT CPU mean the CPU is dead? I had to use the T20 heatsink since T21 one wouldn't fit, could that be the problem?

2. The motherboard in T21 is fried. Do I have to get a motherboard with exactly same FRU number to fix this or it doesn't matter as long as it's T20/21/22 board? Will this board work with any PGA P3 CPU as long as it's 100MHz FSB?

Any feedback appreciated.

[shined]

1. Does the fact that T20 refused to power up with SL4GT CPU mean the CPU is dead? I had to use the T20 heatsink since T21 one wouldn't fit, could that be the problem?

Quite a few people, including myself, have successfully upgraded the CPU of T20 to 1GHz, so I don't see any reason why T20 does not take an 800MHz CPU. So my best bet is that your CPU is already dead as you guess. The heat sink should not be a problem as to whether it boots up or not.
BTW, I'm using a T21 heatsink on my T20 so I don't understand why you say it wouldn't fit. I suggest you try again and let us know more detail of the problem.

2. The motherboard in T21 is fried. Do I have to get a motherboard with exactly same FRU number to fix this or it doesn't matter as long as it's T20/21/22 board? Will this board work with any PGA P3 CPU as long as it's 100MHz FSB?

The physical shape of the systemboard is exactly the same for T20/21/22 so these systembords are interchangable. You don't have to stick to any particular FRU as long as the LCD is XGA. If you have SXGA+ LCD, you need to make sure that the systemboard has a Savage-IX8+. See this thread for more detail.
http://forum.thinkpads.com/viewtopic.ph ... highlight=

[lithium726]

Did you update your BIOS for the 800mhz CPU?

IIRC, the T20 only supports up to a 700mhz with earlier BIOS revisions.