Chosen Solution
I am reassembling my powerbook after replacing the display inverter. I want to put the heat sink back on the processor (and other chips as well below it?), but the thermal paste guide pictures and my situation look different. It appears that any paste is a bit more like a pad than I thought, though the stuff on the processor is likely some thick colored paste. My main concern is with the pads: The pads seem about one or two millimeters thick. Would removing the pad and applying thermal paste lead to a gap and therefore a problem with cooling? If I end up reusing the pads afterall, would I then have to put thermal paste on the underside of the pad? Are there any issues with small irregularities in the pads’ surface smoothness? What if the pads got a little bit of dust on them, probably during dis-assembly of the laptop? Does this present an issue? If so, would it be best to just get replacement pads or use thermal paste? Thanks for your time and effort answering my question.
Personally I’d dump the pads, apply the paste and seat the heat sink. Then remove the heat sink and inspect the paste to see how well contact is being made, then make my decision. If your book looks different than the guide it may be the wrong one. Please give the last three letters of your serial number to insure we’re talking about the same machine. PowerBook G4 Aluminum 12" 1-1.5 GHz Heat Sink Replacement
I’ve never used the pads. The Arctic Silver is the best paste I know of and I’ve never had to replace it. I’m surprised you would know of it, usually only professionals know.
I faced this very issue last month when upgrading the CPU in my Compaq notebook (AMD P320 2.1 GHz dual core to AMD N620 2.8 GHz dual core). After the upgrade, I powered on the notebook, and within a couple of minutes it just shut itself right off. I did this a couple more times. Thinking it was a dead CPU, I tore down the laptop again, and discovered that there was about a 1mm air gap between the GPU and the heatsink. When I did the upgrade, I removed the old GPU thermal pad that was stuck to the heatsink, and rather cavalierly applied Arctic Silver 5, thinking that would do it. Well, after this epic fail, I could see that the AS5 wasn’t enough to bridge the ~1mm gap between the top of the GPU and the copper heat sink surface, so I improvised: I made a heat-conducting shim. Using a sharp knife, I cut a nice, smooth, flat 3/8" x 7/16" rectangular piece of aluminum off a thick foil casserole baking pan (about 1mm thick) that I had lying around. I cleaned both sides of the the shim with 91% isopropyl alcohol, applied thin, even films of Arctic Silver 5 to it and the heat sink (“staining” it), and to the top surfaces of the GPU & CPU. I reassembled my notebook, powered it on, and I’m good to go. Temps on the GPU & CPU get no higher than 67°C at 2.8 GHz fully loaded, gaming, etc., which is going to be typical for this class CPU, and in a laptop. 28% speed improvement, all around. Totally worth the effort. But anyway, yeah…maybe try this aluminum shim approach. Or maybe even copper, if you can find it. Even though copper is about 3 times better than aluminum at conducting heat, I don’t think the operating temperatures would be drastically lower with it. bump
Thermal paste would be better than pads. All the paste/pad does is fill in area’s where the cpu/gpu and heatsink don’t touch (usually very very small), ideally you want full metal to metal contact, but that’s next to impossible. I would ditch the pads and get some Artic Silver 5, you should notice a few degree drop in temps
I’d also really enjoy hearing the answer to this one. The pads seem about one or two millimeters thick. If I end up just using the pads, would I then have to put thermal paste on the underside of the pad? Are there any issues with small irregularities in the pads’ surface smoothness? What if the pads got a little bit of dust on them, probably during dis-assembly of the laptop? Does this present an issue? If so, would it be best to just get replacement pads or use thermal paste? Thank for your answer.
I apologize for not updating to “post my findings here” as I promised. The gap was simply too far from the motherboard without enough pressure to make a thin layer of arctic silver a viable option. As for when you may need to replace the pads, the official recommendation is to replace the pads only if they are damaged (perhaps by removal). I specifically replaced the pads in this computer because it had overheated and I had to separate the heat pipe to replace the fans and wanted to rule out the pads too.
Errol, thanks for replying. What kind of thermal pads did you use? I tried to replace them using ones recommended here: How do I replace heat sink with both thermal paste and pads?. But they were too skinny and very difficult to apply. I doubt it will do much good. In doing so, I removed the pads, partially ripping one (and the other has dust on one of the sides). Maybe I could clean the dust off as best as possible and re-stick both on? If anybody knows what kind of pads would offer nice, thick, sticky surfaces and would be easy to apply, please let me know.
You can replace thermal pads with apropriate thermal paste which is designed to replace thermal pads. Normal thermal pastes should be of high viscocity in order to cover only the very small gaps between the CPU (or other hot component) and the heat sink so there should be in no way as thermal pad replacement. A thermal paste that is designed to replace thermal pads should be very gummy in order to cover big gaps and of very high thermal conductivity. There is one called K5-PRO which is designed for iMac computers but should be fine for any other computer. You can find videos of it on youtube http://www.youtube.com/watch?v=e9v5MDivZ… and it is avaliable on ebay http://www.ebay.com/itm/261419411897 Just search for k5-pro thermal paste
One place that I have found nice thermal pads is on [http://www.frozencpu.com. They have some there made by Fujipoly that can conduct 17w/mk. I have just placed an order for 2 different sets myself and will write my findings when they arrive and I install them on the laptop I have been working on. Student of LIT :)
do[nt use thermal pads use thin aluminum or copper shims with paste to fill in larder gaps where pads used to be ive get 10-20 degrees cooler
