strange problem: adding ram T41p

[ashat]

I have two twins T41p. 2374-GGG.

The one with noisy fan, and dim LCD, has 1Gb ram 512+512.
The other one, still very good LCD, and quiet fan, 512Mb in the slot under the keyboard.

So I decided to switch the additional memory to this second one, but the laptop does not start.
It doesn't even show the initial IBM logo. Power on and the fan starts, but nothing happens.
I have tried two times, same story.

Taking off the additional sodimm the laptop starts regularly.
Putting the sodimm back in place in the other T41p it works perfectly.

What does it mean?
A defective slot?

I can't think to problems of compatibility, the two laptops are the same model, and the sodimm is labelled IBM.

I just noticed the two small covers of the memory slots look different in the inside, different colors, different holes...

A.

[sjthinkpader]

If one of your SODIMMs is an 8 chip design, try that in the bottom slot. Sometimes the machine cannot drive 2x 16 chips (32 chips). Each chip design has slightly different input capacitance and having 16x of a slightly higher capacitance design may just broke the camel's back.

[ashat]

If one of your SODIMMs is an 8 chip design, try that in the bottom slot.

now it is in place in the other T41p and shows 8 chips on one side. So I assume it is a 16 chips, isn't it?
this means it cannot be placed in the bottom slot? the bottom slot is the one under the keyboard, right?

Sometimes the machine cannot drive 2x 16 chips (32 chips). Each chip design has slightly different input capacitance and having 16x of a slightly higher capacitance design may just broke the camel's back.

this means I should look for a 8 chips SODIMM?

A.

[RealBlackStuff]

The bottom slot is the one on the bottom of the laptop, under the removable cover.
Those covers may have different colors/holes, but that has no influence whatsoever.

[ashat]

The bottom slot is the one on the bottom of the laptop, under the removable cover.
Those covers may have different colors/holes, but that has no influence whatsoever.

ok, so what could I try.
check if the sodimm under the keyboard is an 8 chips and eventually switch them,
or look for another 512mb (or 1Gb) sodimm with 8 chips desing, right?

A.

[RealBlackStuff]

Maybe give us all the IBM part numbers and other info on all your RAM modules?
Basically any PC2100 or PC2700 Sodimm should work in any slot...

[sjthinkpader]

Both top slot and bottom slot is actually on the same memory bus. Just make sure one DIMM is 8 chips version.

[ashat]

Both top slot and bottom slot is actually on the same memory bus. Just make sure one DIMM is 8 chips version.

Well, I did try with a 512Mb with 8 (big) chips that I have in my R40, on the bottom slot.
Nothing change, stil no initial IBM logo.
The same SODIMM put in the other T41p works perfectly.

Is this a sentence of "defective slot"?
Am I right that the only way to improve the memory of this machine will be to look for a 1Gb stick and try it in the under-keyboard slot?

The FRU of the bottom slot is the same for both the machine:
FRU P/N: 93P3313

Obviously exactly today the T41p in which the additional memory works has given its first "fan error" message.

It's crazy. I have a dying machine (for the fan, the LCD and the trapped keyboard) able to reach 1Gb ram, and the in "good-health" one unable...

A.

[ajkula66]

Honestly, that does sound like a defective slot.

Good luck.

[ashat]

Honestly, that does sound like a defective slot.

Good luck.

Should I got a confirmation with something like PC-doctor?
I never used it.

A.

[ashat]

Well, I did try with a 512Mb with 8 (big) chips that I have in my R40, on the bottom slot.
Nothing change, stil no initial IBM logo.
The same SODIMM put in the other T41p works perfectly.

Is this a sentence of "defective slot"?
Am I right that the only way to improve the memory of this machine will be to look for a 1Gb stick and try it in the under-keyboard slot?

A.

just to know: Corsair vs Kingston here in Italy a new 1Gb dimm PC2700 costs 44 vs 71 euros.
Is Corsair good enough or should I spend this additional 27 euros?

A.

[sjthinkpader]

Just run memtest86 to make sure it is good. That slot may just need a solder touch up. There is a good shop in UK in the stickies.

[ashat]

If I can put 1Gb in the under-keyboard slot it could be enough to me.
Is it compulsory to unplug the keyboard to make the operation or can I just put it apart without unplug?

A.

Just run memtest86 to make sure it is good. That slot may just need a solder touch up. There is a good shop in UK in the stickies.

[RealBlackStuff]

You need to unplug the keyboard, otherwise you can't get at the right side of the RAM module.
It takes only seconds to unplug, and seconds to plug it back in.

[ashat]

You need to unplug the keyboard, otherwise you can't get at the right side of the RAM module.
It takes only seconds to unplug, and seconds to plug it back in.

Ok, thanks a lot,
I will try as soon as I will find a 1Gb memory stick,

A.