Long Heat sync faNS

[SkipHK]

My old T40 has had a history of failures every couple years attributed to the video chip... all done under warranty. Popular thinking is it overheats thus fails. I took a chance and replaced it with a used motherboard and it works fine. The mothrboard I got was a different FRU number form either of the warranty replacments. I have no way of determining if it is for a T41 or 42. I doubt it's for a T43, In any case it works.

I would like to locate the proper long heat sink fan which covers the video chip but there are about 8 different part numbers it seems. The visual difference is that extended protusion that makes it "long" can be wider than others. On some the extension only covers a dinky chip which I suspect may be the video chip. On others it is almost the width of the main part of the fan assembly and looks to cover a larger chip close to it.

Can anyone educate me on the chips the wider extension can cover. Even better... how do you cross reference a motherboard FRU part number to which T4X so I can know for sure what I eneded up with and get the correct longn heat sink fan.

Skip

[RealBlackStuff]

If you give us your mobo P/N or FRU, we may be able to help you further.
Open the RAM lid at the bottom, remove the RAM, and there you find the P/N or FRU.

[SkipHK]

It's a 93p4156

[poshgeordie]

Hi Skip

your board is from a T42 and has the ATI Radeon Mobile 7500 graphics chip.

To cross reference the boards etc, refer to the Hardware Maintenance Manual which lists all (well, some anyway!) part nos.


The best way to solve the unsoldered chip problem is to carry and move the laptop correctly - no lifting by the front edge, corners, lid, which will cause the motherboard to flex. I know we all know this, but even so this leaflet is a good reminder.

I'm not sure if fitting a heatsink over the graphics chip will be more beneficial than allowing the free movement of air over it in the long run, especially since the chip's not designed to have a heatsink on it.
However the R32 does have a heatsink over a similar graphics chip (same as the 7500 with only one memory chip)

My 3c's worth!

[SkipHK]

Thanks for the reponse Nick. The manual says the original video chips were Radeon 7500 too. After looking at your "little flyer" as I reflect back I know I did this often. I will definately take more care. Your comment about how much good the long heat sink fan would do leads to another query..

I know the standard heat sink is the short verson. Do you know what caused them to to become a part to begin with? The ones I see on E-Bay all indicate for the T4X series... do you think they tried to solve a heat problem by coming up with the long heat sink after so many problems... as an after thought solution?

In my intitial two year warranty (after new) I had my motherboard replaced for the same video graphic reason. It took them three boards to get one that worked for more than a few days. The service shop indicated that the replacement boards they got from IBM (back then) were refurbed boards and it was hit or miss as to getting a good one. A couple years
later under extended warranty that board went bad as well. Maybe that's why IBM sold out to Lenovo!!! )

Any comments on the matter from you or others is most appreciated... I am having second thoughts about putting more money into the laptop. I do like having a reliable spare..

[SkipHK]

One more question...

If I opt for the long heat sink fan do you think that grease between it and the heat sink is needed? The surface that fits over the 7500 chip is not a flat copper surface like over the processor... it has some kind of white material on it.

[poshgeordie]

Hi Skip

You've raised some interesting points.

The various boards fitted to T40-2-p series also had different graphics chips fitted.

For instance board FRU 93P4158 is fitted with the Radeon Mobile 9000, and 93P4159 with the FireGL graphics chip.

Both these have metal top covers which are heatsinks and need the long heatsinks 13N5442 or 13R2657 (sorry - not sure which is used for which board/chip - lack of time at the moment!).

The point is that these long heatsinks are used for graphics chips with "metal-top" heatsinks. The height of these graphics chips are likely to be higher than a non-heatsink "plastic-top" 7500 so may not sit properly on a 7500.