Missing GPU aluminium shield

[dsg22]

Hi all,

I have a T43 I'm trying to patch up. The GPU thermal sensor was reporting very high temps (idling at ~88-90°C). I took it apart and it turns out the heatsink does not make contact with the GPU.

Looking at pictures of others' motherboards, it looks like the ATI chip is supposed to have an aluminium plate on top that contacts the heatsink. Mine is missing this plate, so there's a good bit of space between the chips and the heatsink.

I cut up an old heatsink to get a couple of small plates that I put between the keyboard and the heatsink to press it downward. Combined with a chunk of thermal paste, this (very ugly) hack brought the GPU temperature to ~76-78°C at idle. However this is still too high for my taste.

I was hoping someone here could give me some information on this GPU aluminium plate. How thick is it supposed to be? Is there some thermal pad underneath it (on the GPU chip, there are three packages protruding upwards, and one of them is lower than the other two, so a flat plate wouldn't make contact with all three)?

Is this plate part of any lenovo parts kit? It is not part of the heatsink kit at least.

Thanks in advance, this forum is great - I'm planning on doing a SATA mod for this machine soon if I get this fixed.

[ajkula66]

Welcome to the forum!

The easiest way to go about this would be to obtain a genuine cover - anything from 9000/9600/Fire GL T2/X300/X600/V3200 will work.

I'm sure that there's a bunch of folks around here with dead T4x board that wouldn't mind shipping you one for a few bucks. Unfortunately, I got rid of all of my dead planars this past week...

Just post a WTB (want to buy) ad in the forum's Marketplace and see what happens.

Good luck.

[dsg22]

Thanks

I ended up fixing this by buying a thin plate of copper, and sawing it to the appropriate size. I put a small plate on top of the GPU IC package to make it almost-level with the GPU RAM ICs and then put two larger plates on top of that. The GPU now idles at around 60°C, which is good enough for me.

The plate I used was 0.7mm which was a bit too thick. 0.5mm would probably have been a better fit, but they didn't have anything thinner.

[FTC]

Hi, this is good, and hopefully you did it well, however one suggestion is now to check the CPU temp. I have done simiar hacks in the past and remember that the problem is to keep good contact for both the GPU and the CPU, being the heatsink a single part for both.

[poshgeordie]

FTC has a good point, but there is a problem using just one copper plate.

Some (and maybe all) original Aluminium GPU heatsinks have a raised section to contact the actual square GPU part of the chip, with the rest of the heatsink contacting the slightly higher VRAM chips (if you see what I mean!).
Using a single copper plate may not actually contact the square GPU part of the chip and could lead to GPU overheating, despite what your temperature readings show.

Check if the parts of the chip are at different heights and use a small piece of copper sheet (shim) over the square GPU heatsink, so the top of the shim is level with the top of the VRAM chips. Then use a second piece to cover the whole chip. Clean off all remaining old heatsink and heatsink adhesive from all parts of the chip using an alcohol based cleaner.

I then suggest removing the old fabric / plastic pad on the GPU part of the main Heatsink Assembly and any old black "gunk" - use a combination of an alcohol based cleaner and scaping with a non metalic tool to remove it - and use a thicker piece of copper sheet on the GPU so the copper sheet contacts the main Heatsink Assembly directly.

Apply very thin layers of Arctic Silver (AS) heatsink compound between the copper sheet pieces and on the square GPU heatsink as well. Don't use AS to fill big gaps - it's meant to fill the microscopic imperfections between touching metal surfaces.

As FTC says, make sure the main Heatsink Assembly is properly touching the CPU as well as the GPU. The easiest way is to apply very thin layers of AS on the CPU and over the GPU copper plate and screw the Heatsink Assembly into place; then remove it and check the AS marks for proper fitting of the Heatsink Assembly to both chips. If necessary alter the thickness of the GPU copper sheet.

This will result in the most efficient cooling for CPU and GPU chips and will be a very good modification.