M-6850FX heatsink

This is just an informational post for anyone who may be having the same
problem I did.

I have a Gateway M-6850FX notebook with the ATI Mobility Radeon HD 2600 and
Windows Vista Home Premium, and it seemed that I was always running high GPU
temperatures. According to HWMonitor, I was running in the mid 50's C. to
high 60's C. at idle, or very low CPU load. Running very graphics intensive
games such as Painkiller or BioShock, I have logged temps as high as 109C.
That can't be good! Upon contacting Gateway Support, I was pretty much told
to try lower resolutions or not to run them at all. Then I was told I could
send it in and they'd take a look at it if I wanted to (it is under
warranty). After sending them a defective hard drive shortly after
purchasing it, and never getting a replacement (mailed back in 12/08), I
decided not to risk them losing my whole notebook, too. The heatsink and fan
assembly is very easy to get to and remove; it's only 7 screws and one
electrical connector for the fan. After removing the heatsink and pipe from
the GPU and CPU, I saw that the heat tape for the GPU was dried and
cracking, and the tape for the Northbridge chip (I believe that's what it
is) wasn't even touching the chip! The only one that seemed to be stable was
on the CPU. I cleaned everything off well, and placed the heatsink in
position, and tried to see under it. No joy. I used layered pieces paper
held together with heatsink grease on it to build up until it touched both
the heatsink and the chips. There was a gap of ~.015" between them! The only
one that was actually touching was the CPU. I have some nice flat .015"
aluminum shim stock around, so I cut two pieces, one each for the GPU and
the Northbridge chip, polished them nicely with some 800 grit crocus cloth,
held them in place with some Loctite heatsink paste, and put the whole thing
back together, being careful about tightening in the sequence listed and a
little at a time. I turned it back on, and my idle temp is less than 45C.
Running Painkiller for half an hour brought it up to 88C. Much better than
it was.

I don't know if mine is an oddball, or if it is a poor engineering design on
Gateway's part, but I think that much of an air gap is way too much to be
filled in with heatsink tape. The stuff is designed to fill in slight
imperfections in the mating surfaces, not fill in that large a gap. I'd call
Gateway and try to find out about it, but I doubt seriously if I'd be able
to get in touch with anyone that had the slightest idea of what I was
talking about.

I hope this helps anyone with a similar family-line notebook.

SC Tom