Thermal Paste vs. Thermal Pad

jrsx

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Nov 2, 2013
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So I don't know much about thermal pads and pastes beside to keep a computer from overheating a lot, they should be replaced every 5 years. Well, my iBook G4 hasn't ever had the paste or pads replaced, so I thought it might be worth it sometime. From what I've read on other sites, thermal paste is easier to apply, but I think my iBook G4 has thermal pads. I don't really know the difference, so can someone help me here? Apple must have used pads for a reason, but should I buy new pads, or new paste? Also, did Apple use thermal pads because the heatsink is so close to the processor (I mean really close)?
 

Intell

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Jan 24, 2010
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If the iBook is anything like the 12" Powerbook, you'll want to use pads. The 12" Powerbook's heatsink doesn't make good contact with the GPU without a pad. I know for most (all?) of the 12" Powerbooks, the have a pad on the north/south bridge chip as well as the GPU, but only paste on the CPU. I'd keep the pads if there are already pads there.
 

jrsx

macrumors 65816
Original poster
Nov 2, 2013
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Tacoma, Washington
If the iBook is anything like the 12" Powerbook, you'll want to use pads. The 12" Powerbook's heatsink doesn't make good contact with the GPU without a pad. I know for most (all?) of the 12" Powerbooks, the have a pad on the north/south bridge chip as well as the GPU, but only paste on the CPU. I'd keep the pads if there are already pads there.
That picture I posted above is an iBook G4's heatsink. Are those pads?
If so, that's what I have right now. If I don't need to replace them, I will just keep the pads I have right now. I've heard pads don't need to be replaced often, but paste does, because it can diminish after a while.
 

Intell

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Jan 24, 2010
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Yes, the two blue things and the grey thing are thermal pads. They typically don't need replaced unless they are torn, too squashed to make contact, or are brittle.
 

gavinstubbs09

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Feb 17, 2013
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I'm one for paste, as it should dissipate heat much better and can lower temps with less fan noise. However on things that don't make nearly as much heat like the chipset, should be fine with pads. CPUs and GPUs should use paste.
 

Cox Orange

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Jan 1, 2010
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... The 12" Powerbook's heatsink doesn't make good contact with the GPU without a pad. ...
I was always under the impression that Apple used thermal pads because the space between the die and the heatsink wasn't perfectly flush, so the added thickness of the pad helped fill the void?...
That both I find a plausible reason. (The Sawtooth CPU-heatsinks have these very thin dark grey pads, with an aluminium layer between it. I wonder, if it is just for saveness - and maybe ease of production.)

Strange though, that ifixit recommends replacing the pads in the ibook/PowerBook on the GPU and put AS5 on it.

It might be something like: save (pad) contra better heat transfer (grease/paste). If better heat transfer is really the case (considering how the x-book heatsinks are screwed to the chips and that the paste may dry out?).

Additionally it would be interesting, if a modern pad is capable of transfering more heat vs the stock pads. In testing this, I see the problem, that one probably could not tell, if the screws were just differently hard pushed.
 

Intell

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Part of the problem with the 12" Powerbook and iBook's heatsink is that they don't have any screws over the GPU like they do with the CPU to provide proper compression. That's where the pad's thickness helps to make contact. The shear amount of paste needed to make contact would be less thermally conductive than a pad. The best thing would be a thin copper shim with paste on both sides of it.
 

AmestrisXServe

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Feb 6, 2014
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Part of the problem with the 12" Powerbook and iBook's heatsink is that they don't have any screws over the GPU like they do with the CPU to provide proper compression. That's where the pad's thickness helps to make contact. The shear amount of paste needed to make contact would be less thermally conductive than a pad. The best thing would be a thin copper shim with paste on both sides of it.
That is the way to go, if you have the option: Copper, with a thin paste layer on each side. (Silver is a far better conductor, although I am not certain how much of an oxidising agent the thermal paste would be.)
 

Cox Orange

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Jan 1, 2010
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I always get confused over conductivity (I mean not thermal, but electrically conductive) or being capacitive and so on regarding the different metal ions in thermal paste in connection with heatsinks. Can someone clarify?
 
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teamd

macrumors newbie
Sep 23, 2014
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Don't ever use thermal pads again!! If there is a gap between the cooler and the GPUs, measure it and buy copper shims and AS5. My riMac now gives me artifacts and restarts and it gets HOT very fast. Much worse than the factory used thermal paste. I used a 6w/k Arctic thermal pad.
 

Gamer9430

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Apr 22, 2014
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Don't ever use thermal pads again!! If there is a gap between the cooler and the GPUs, measure it and buy copper shims and AS5. My riMac now gives me artifacts and restarts and it gets HOT very fast. Much worse than the factory used thermal paste. I used a 6w/k Arctic thermal pad.
We appreciate your input, however, we'd also appreciate if you didn't dig up ancient relics on the forums ;)... Thanks and welcome!
 

teamd

macrumors newbie
Sep 23, 2014
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I am sure you have better things to do than to pick on me, for writing on subject, which you are not.
 

teamd

macrumors newbie
Sep 23, 2014
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That happens when you don't mind your own business :), whats the problem with reviving an old thread? Its an useful information and you are trolling, of course you are going to get these kind of answers. Simple as that
 

bunnspecial

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May 3, 2014
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The oldest retina iMacs would be just barely over a year old now. I can't imagine first of all not buying Applecare on a newly introduced Apple product, but also unless you were an early adopter that the machine is out of warranty.

Personally, I'd let Apple fix it at least while it's under warranty and not engineer my own cooling solutions(which will surely void what you remaining warranty you have left).

In any case, the overlap between folks who frequent the PPC forum and folks who own a retina iMac is quite small-I think there's only one regular here who has one. This would likely have been better received in the retina iMac forum.
 
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Cox Orange

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Jan 1, 2010
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Don't ever use thermal pads again!! If there is a gap between the cooler and the GPUs, measure it and buy copper shims and AS5. My riMac now gives me artifacts and restarts and it gets HOT very fast. Much worse than the factory used thermal paste. I used a 6w/k Arctic thermal pad.
Thanks for your input. I don't mind you dig up an old thread, because the info is still useful and I get automatically informed about new posts (if you had put it elsewhere, I might have missed it). BUT, I agree with bunnspecial, I don't know how much comparable a retina iMac is with PowerPC-Macs, or the ibook G4.
My bad, I also didn't realize until the last post, that the "r" in riMac is for retina, I thought you hit the keyboard accidently ;) but now it's obvious. :)

PS: now that this topic is on top of the forums again, I'd too like to add info. Here is a roundup of several thermal pastes (of course one can argue, if the differences are more like differences coming with testing methods and such). http://skinneelabs.com/2011-thermal-paste-review-comparison/2/
 
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teamd

macrumors newbie
Sep 23, 2014
20
5
I solved the problem by replacing the thermal pad with a Shin-Etsu thermal paste. I didn't really matter that it was a rImac(i realized the r stands for retina a few days ago too lol) the thermal pads just don't do the job. The difference in temperature now is about 30 degrees C in full load and no restart/artifact :)
 

teymur

macrumors newbie
May 28, 2015
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Did anybody try the alternative with a copper shim & thermal paste between heatsink and CPU yet?

I was thinking about trying it on my iBook G4 1,33Ghz some day, but I'm still sceptical, as the copper shim doesn't have any flexibility like the thermal pads do. And there are no springs on the iBooks heatsink to balance the pressure applied by the screws.
 

MilesJ

macrumors newbie
Apr 29, 2016
1
1
I am using the copper shim method and I gotta say it pretty good. Copper shim has greater conductivity than any pads and combined with them it just does wonders for my laptops.
I am using K5-PRO and K4-PRO thermal pastes. K5-PRO is designed to replace thermal pads (like the one apple uses) and it is the only commercialy avaible product that can replace thermal pads (as far as I know).

There are a lot of videos on youtube that can guide you through the replacement process if you don't how to do it like so:

Hope this helped!
 
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for this

macrumors 6502
Nov 18, 2014
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Just opened my iBook G3 last month to repair display's cables and accidentally damaged the original thermal pads of the CPU and an unknown chip nearby. Replaced them with 0.5mm (for the CPU) and 1.5mm (for that chip) thermal pads from Arctic Cooling. All has been well even with heavy tasks.
 
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Strider64

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Dec 1, 2015
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I have been building/repairing computers since 2000 and even got certified as a PC service technician. TIM is better when it's a paste, for covers the surfaces better between the heatsink and cpu/gpu. Think it as waves in an ocean that doesn't move, which is going to cover the valleys (I think they're call troughs? ) better? Answer: Sand or a Spongy Material? Obviously the answer is sand. Just as past would be over a pad. Though in this case I probably would go with thermal pads for that was what was originally put on. Though I think paste would work just as well if not better.
 

Cox Orange

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Jan 1, 2010
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@Strider64
though people here have mentioned that the space between die and heatsink is a bit bigger, so I wonder, if a pad wouldn't make up better with the gap.