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HP G62 Laptop Heat Pipe Issue


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#1 Byff

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Posted 30 September 2017 - 03:52 PM

I've done a tear-down on my trusty G62, which has developed cooling problems over the past couple months.  The cooling fan wasn't particularly dusty, but I did clean it out.  I've replaced the thermal paste on the CPU and GPU, and done a perfunctory check of the heat pipe to see if it might have sprung a leak at some point.

 

I'm on the point of reassembling the machine now, but two things stand out to me that I want to get some advice on before I screw it all together.  Whereas the CPU's preexisting dab of thermal paste had run free and slopped over the sides of the die, the GPU doesn't appear to have had much at all on it.  There was a pad of thermal material adhering to the heat pipe at the putative junction of pipe and GPU die, but it doesn't appear to have ever actually bridged the gap.  In other words, the GPU was apparently never in contact with the heat pipe.  The bend in the pipe that would have sandwiched the thermal pad between pipe and GPU is too shallow.  (Note that I'm positive I didn't introduce any bending or unbending to the pipe when removing it.)

 

The idea is to eliminate the air gap, but I don't want a layer of goop 1/8" thick on the GPU either.  I have some scrap copper I could cut to fit, and use some paste on either side of it to shim the die up to the heat pipe, but I have no idea how well that would work.  (I suppose it couldn't work worse than the air gap, which presumably has been all the "cooling" that GPU has had since the laptop rolled off the assembly line.)

 

Any ideas or advice?  Is this a known issue with these laptops?  Should I try to locate a replacement heat pipe?  I'm living at essentially college-student level economy right now, so that would be an unfortunate expenditure to have to make, especially if the replacement part has the exact same profile as the current one.

 

Thanks in advance.

 



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#2 JohnC_21

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Posted 30 September 2017 - 04:05 PM

I don't know if you have the service manual but page 80 shows the location for the Thermal Paste.

 

http://h10032.www1.hp.com/ctg/Manual/c02542102.pdf

 

And a video. The GPU heat sink looks like it's using Thermal tape/pad.

 

And another video

 

If you have already seen the above, sorry for posting.


Edited by JohnC_21, 30 September 2017 - 04:05 PM.


#3 Byff

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Posted 30 September 2017 - 05:33 PM

Cool, thanks.  Now I have the service manual.  :)

 

It seems to indicate that I should be using pads and paste.  The illustrated section in question says material must be applied to all surfaces.  The CPU and pipe are in good contact, with paste between them, but it seems I should use the pad (which I retained) and some paste for the GPU.

 

I guess it's safe to experiment a bit in this regard, since there was probably no contact at all before now, and the system was (apparently) shutting down before any real damage occurred.  (Any experimentation to take place pending watching the videos.)


Ah.  I think I've already watched both these videos, but am currently reviewing...



#4 JohnC_21

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Posted 30 September 2017 - 06:29 PM

I never heard of using paste with a thermal pad. Newegg has thermal pads up to about 5mm thick. In the first video I noticed paste was applied to the CPU but nothing was done to the GPU chip. It seemed the heat pipe was replaced without paste added

 

https://www.neowin.net/forum/topic/91593-thermal-pad-thermal-paste-bad/

 

I did find this where a poster recommends a particular paste to replace the pads.

 

Personally, I don't think you should reuse the pad.

 

Thermal pads should be replaced with thermal pads only or with specially designed viscous thermal paste. The reason is that normal thermal paste is not designed to fill big gaps so sooner or latter will flow out and leave a gap between the component and the heat sink.Apr 20, 2015

https://www.ifixit.com/Answers/View/224551/Can+I+use+thermal+paste+instead+of+thermal+pads


Edited by JohnC_21, 30 September 2017 - 06:30 PM.


#5 Byff

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Posted 30 September 2017 - 07:04 PM

OK.  So I should consider waiting to close it up until I have some thicker pads to try.

 

In retrospect, the GPU was probably always at issue to some degree.  The fan always quickly kicked into high gear when I connected a secondary monitor via VGA, and would also eventually start cycling when I connected one via HDMI.  But I've used the laptop for five or six years without any real issue until this summer, when it started bluescreening at random.  I don't suppose it's possible that the pad just separated spontaneously from the GPU, causing the air gap...?  There is a squarish indentation indicating the GPU die once pressed into it.  The pipe just doesn't seem to have the right degree of bend to it, and I can't think of how or why it would have flattened out since leaving the factory.

 

Something else just occurred to me, though.  About three years ago, on or about Christmas of 2014, I knocked the laptop off a desk, causing it to fall hard onto the floor.  The impact head-crashed the HDD, and I had to buy a replacement, reinstall the OS, and do data recovery from the old disk.  It does seem to me now that I started noticing the laptop running warmer from that time, and I blamed the new HD.  But maybe instead the pipe was knocked free of the GPU, in which case there's probably some means of refitting it into place like factory new.

 

But I'll look into obtaining some new pads first.



#6 Byff

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Posted 30 September 2017 - 07:09 PM

PS.  The second link you provided suggested something similar to something I'd already considered.  I came across a piece of scrap copper at work yesterday that could be used to bridge the gap if I can flatten it properly.  I suppose thermal paste would have to be applied to both sides, but the thickness would be just about what is needed to connect the GPU to the heat pipe.



#7 JohnC_21

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Posted 30 September 2017 - 07:17 PM

I think using a copper shim with thermal paste on both sides is a good idea. Newegg sells copper shims for the same purpose. I think that would work better than a single think pad or paste.



#8 Byff

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Posted 30 September 2017 - 09:29 PM

Bwahaha.  I reassembled it to test it with just the thermal paste in place, and it looks like I have to partially tear it down again.  Although all systems are go, the keyboard ribbon cable is evidently misaligned.  (The evidence?  When I was attempting to enter my password, it was logging some keystrokes but not others...and Backspace showed up as a character, rather than deleting anything.)

 

At least I know the system isn't borked.  I found some copper shims and some pads online, and will try the shims next if overheating persists.  But I'll call this issue closed for now.

Thanks for all the advice, guys.






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