T42p fan long m10 installation : pink sheet or not...?

[agarza]

I removed the heatsink about 1 month later when I received my laptop, but also had the pink sheet.

[Oldgeezer]

An observation, respectfully offered :

The Hardware Maintenance Manual for the T42p, dated February 2006, has the following entry, referring to Fig (b) of page 106:

“Only in the case of Fan assembly, long, you need to peel the plastic sheet b off on the thermal rubber before you place it on the system board. Fan assembly, long M10 DOES NOT have the plastic sheet.”

(this is verbatim, syntax and all)

I have just replaced the fan on my T42p (which was making grinding noises most likely due to a failing bearing) with part number 41W5204, a new part from IBM. I removed the stuck heat sink plate from the GPU by abrading the hardened black thermal compound at a corner using some dental floss, until I had enough room to slide a flat tweezer blade horizontally between the copper plate and the top of the GPU, and with carefully controlled horizontal force. As the tweezer blade grows in thickness slightly it separates the copper from the GPU as it is forced inward, and eventually the adhesion of the black compound broke loose. There was no original pink sheet. About 10 minutes of teasing did it.

The hardened black heat transfer compound still stuck to the GPU did not readily dissolve in either isopropyl alcohol or ethanol but cleaned up very well with acetone. The CPU heat grease was not hardened and cleaned very easily.

I then installed the new fan followed the HMM directions above exactly. The new fan came pretreated with a gray-silver heat sink compound laid out in a precise array of dots in the CPU contact area, and with a thin black compound covered by the famous pink plastic sheet over the GPU area.

The HMM instruction very clearly contradicts all of those individuals who are advising to keep the pink sheet on. Because I am sure that they have access to the same manual that I have just quoted from, it begs the question why do they differ?

I can think of one reason why they do wish to keep the pink plastic sheet covering the black compound, thereby raising the thermal resistance between the GPU and the fan-cooled copper plate: They wish to be able to remove the fan repeatedly, without the need for floss and tweezers, for later maintenance or for hobby purposes. This is a valid reason, but it seems that one pays for it with a higher thermal resistance.

Am I missing something? I would like to learn the facts that drive this sentiment to keep the pink sheet in spite of IBM instructions to remove it.

(My thanks to all that have come before and to all that reply.
This is a wonderful forum!)

[Tim M]

Am I missing something? I would like to learn the facts that drive this sentiment to keep the pink sheet in spite of IBM instructions to remove it.

Not to contradict your observations, but the OEM long fan installed in my T42 came with both the black rubbery material and the pink sheet. These were revealed during a motherboard replacement. One possible explanation is that I (think) the M10 is a more recent variety of the long fan. Alternatively, perhaps there is a clear plastic protective sheet over the pink sheet on replacement fans and that is what is referred to in the HMM.

In my case, the pink sheet on the OEM heat sink was damaged (cut) during removal of the fan assembly, but temperatures after installation on the new motherboard have been fine nonetheless. Idle GPU temperatures are around 50-55 C; a "torture" load test pushed it to 90 C, which I consider acceptable for sustained 100% load of CPU and GPU for ~30 minutes.