Roll Cage's Play in Heat Disbursment

[wswartzendruber]

Does the roll cage play a particular roll in disbursing the system's heat? If not, can the internals be modified to accomidate this? What (theoretically) are the reprocussions?

[Troels]

No, not in particular - and magnesium does not conduct heat as well as even aluminium, so how much is gained by any modifications should be low.

The only place where the heatsink touches the roll case is by the metal bracket mounted by two screws over the GPU section.
The T61 uses the underside of the keyboard to get a larger surface for dissipation.

The largest problem is with the heatsink compound inbetween the heatsink and the gpu. I replaced mine with a piece of aluminium, which lowered the temperatures by 15-16 degrees C, so that the maximum load temperature is 83 degrees C on a hot day.

[hellosailor]

Troels-
"the heatsink compound inbetween the heatsink and the gpu."
I'm curious to understand that. Did you replace a piece of adhesive transfer tape? Or remove some typical "thermal goo" and stick in an aluminum shim instead??

[Troels]

There was no adhesive transfer tape.
I removed the thermal goo (Blu Tac?) and glued an aluminium shim to the heatsink with Arctic Silver Adhesive (some sort of epoxy) so that it had proper contact. Where the surface met the GPU, i put on some arctic silver 5.

The required shim does need to be around 1.5 mm, but i can measure the exact thickness i used if needed.

[hellosailor]

Am I misunderstanding, or are you saying there was a 1.5mm gap between the GPU and a heatsink that was supposed to be directly in contact with it? That would seem like a gross error, heat sinks are usually very carefully bonded.

[Troels]

Not an air gap, but a 1.5 mm gap filled by goo.
That is, the thickness of the goo between the GPU die and the heatsink was aproximately 1.5 mm.
This heatsink is for a widescreen T60p, but it shows the same thick layer of goo: http://img.chrosmack.com/images/41W6409 ... 051208.jpg
I wish i could find better close-up pics, but i couldn't...

[DarkScythe]

What's he's trying to say is that while the heatsink itself is quite flat, the location of the GPU is actually LOWER than that of the CPU, meaning that there is a "gap" between the heatsink and the GPU, and thus, is filled by some sort of thermal goo, which really does seem like blu-tac when I opened mine up. Unfortunately, I did not have the available tools to mod mine so it remains filled with that goo.

[hellosailor]

Looking at the two squares top left rear in the picture? That look like double-stick foam tape, sort of?

If that's what came off the CPU and GPU...it looks like thermal transfer tape, and supposedly the whole design is made to accomodate the way it works. But you're right, a metal-to-metal contact with a layer of old fashioned thermal paste (silver, white, whatever) would keep the chips cooler than that.

I'm still under warranty though, so I won't be pulling mine apart to "improve" that. Most of what I do hasn't stressed anything beyond nominal operating temps--yet.<G>