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Pennstate · Jun 4, 2006, 03:03 AM

Hi folks,

Inspired by thermal-paste reapplications in the new macbooks and macbook pros, I tried it on my 12" 1.33ghz G4 powerbook. The difference was about 8C degrees (53C idle before, 45-6C now). What's awesome is that the bottom of the PB doesn't get hot any more, just warm. I can now use it on my bed without having a flat surface underneath. This was very comparable to my IBM T42 centrino. It became a "lap"top again. The fan also doesn't come on as often now. Sorry I didn;t take any pictures, but here are some tips:

The heatsink assembly spans over the cpu, the gpu, and the motherboard chipset(?)
Only the cpu can directly contact the heatsink. Therefore, do not damage the thermal pads on/over the two other chips. Or else, you will end up with a pretty big gap between those chips and the heatsink.

There are two places where you can apply arctic silver. on the CPU, and on the top edge of the heatsink that contacts the LCD hinge (?) The top edge enables the whole case to be used as a heatsink.

I thoroughly cleaned up the thermal paste gunk on the cpu, which was a bit sloppily applied. I also cleaned up the heatsink. A very thin and even layer of arctic silver was applied to the top of the cpu and on the top edge of the heatsink. The heatsink assembly was then carefully placed back in its place. When putting the screws back in, make sure you start with the 2 spring-loaded ones that are right next to the cpu. This will ensure good contact between the G4 processor and the copper pipes on the heatsink. Other than that, it was pretty straight forward.

Use an ice tray to store all the screws or parts in order. Apple use many different sizes for screws. You can short the motherboard if you use the wrong screw.

It was all worth it. I debated whether to spend ~$400 to get a macbook (sell PB, buy ram, bigger hard drive for the macbook). In the end, I decided that I like the PB g4 keyboard much more than the MB. And the portability of the 12" PB was unbeatable. I ended up spending $340 on a 20" widescreen LCD from DELL. Maybe it's just an illusion, but I think my PB feels much more snappy when I have it connected to the 20" LCD. I'll wait until apple comes out with a worthy replacement for the 12" PB.

harrisjamieh · Jun 4, 2006, 03:14 AM

Originally Posted by Pennstate

Maybe it's just an illusion, but I think my PB feels much more snappy when I have it connected to the 20" LCD.

I have always found that connecting notebooks to either an external mouse, monitor, or both gives the illusion of the machine being quite a bit faster. I know its only an illusion, but its weird you notice it too!

jpuckrin · Jun 7, 2006, 12:29 AM

Great idea,
I am going to do this on the weekend. Any other tips before I jump into it? I'll take some pictures and post my results here.
-Jonathan

ibook_steve · Jun 7, 2006, 01:23 AM

In the 12", I know for a fact that there is no thermal paste used. All three chips (CPU, GPU, and Intrepid) have thermal pads that either squeeze or melt into place.

Steve

jpuckrin · Jun 7, 2006, 02:19 AM

Originally Posted by ibook_steve

In the 12", I know for a fact that there is no thermal paste used. All three chips (CPU, GPU, and Intrepid) have thermal pads that either squeeze or melt into place.
Steve

Could this just be different rev. of the Powerbook or do all powerbooks only have pads?

Pennstate says

I thoroughly cleaned up the thermal paste gunk on the cpu,

so what are you taking off then Penn?

Also might be worth noting how different my Powerbook 12" 1.33 is from my G/F's ordered over 5 months later are.

ibook_steve · Jun 7, 2006, 01:24 PM

No. They all use pads. I kept a set for my 12" after I left Apple. Like I said, the pad on the CPU squeezes and melts over the chip to form a firm seal. That's why it looks strange, and, as I've mentioned here before, this is probably what is in the MBP as well. Applying thermal goo on a factory line during assembly would be a real pain. A melting pad makes the process much easier and faster.

Steve

Eug Wanker · Jun 7, 2006, 02:10 PM

The pix for the MacBooks from the manual specifically show to use thermal paste.

ibook_steve · Jun 7, 2006, 03:07 PM

Yes, those are for technicians who would not have sets of Apple's pads. Goo from a tube is not used at the factory.

Steve

jpuckrin · Jun 7, 2006, 03:53 PM

Alright, well then your saying iBook_steve that there is nothing wrong with removing the pad and using AS paste then, your simply stating that they don't use it at the factory. Correct?

ibook_steve · Jun 7, 2006, 03:58 PM

You can do whatever you want with your machine, though you would cancel any warranty you have left. But you are correct. They don't use thermal paste during assembly at the factory.

Steve

Velocity211 · Jun 7, 2006, 04:09 PM

Does the 15" Powerbook use pads on the GPU? Because the sensors always say 200+ I overclock it a little bit to play Quake 4 with some decent framerates. (Yes I know i will fry it overtime...)

icruise · Jun 7, 2006, 04:24 PM

My 1.33ghz 12" PowerBook G4 really doesn't get hot at all unless I am encoding video or something. Under normal circumstances, it is quite cool. The MacBook/Pro is one thing, but is it really necessary to try something like this on a G4?

Dr.Michael · Jun 7, 2006, 05:02 PM

Originally Posted by Icruise

My 1.33ghz 12" PowerBook G4 really doesn't get hot at all unless I am encoding video or something. Under normal circumstances, it is quite cool. The MacBook/Pro is one thing, but is it really necessary to try something like this on a G4?

No, I don't think so. I thought about this when I learned that my (now sold) 12 inch powerbook used the fan very frequently when it was connected to an external screen. So I opened the machine and had a look, if I could find weaknesses. I could not. To be honest, Apples engineers did a good job and have designed a well done heat sink.

I am sure that a very thin layer of thermal paste will increase the heat conduction compared to the relatively thick thermal pads. But I doubt that this will bring down the temperature in a way that the fans run less frequently when an external screen is connected. Without screen the powerbook does indeed not get so hot.

You really have to be clear why you want to do this. If the fans annoy you - there is a chance that the situation might improve. If you think the machine gets too hot - NOOOO. The G4 is in no danger at all

. Besides, its the GPU that produces the heat in the 12inch powerbook.

And the Macbook? All these specialists here should start to check the specs of the core duo. It is specified for up to 100 degrees C operating temperature!!! 77 or 85 are perfectly OK. And as long as the machines run quiet - whats the point? Are you bored with life? Don't you have something useful to do?

jpuckrin · Jun 7, 2006, 05:15 PM

It's been out of AppleCare for some time now.

#1 lower operating temperatures for something simple like replacing the pads with AS V is a worthwhile endeavor to myself.

#2 I have an early version of the 1.33 and I tend to put some work on my machine. The fan kicks on after about 3 hours of use. In class the fan kicking on is a small annoyance, but I would venture to say still 80% quieter then the windows laptops in the room. General E-Mail and web surfing the fan never kicks in.

#3 This wouldn't be the first nor will it be last time I open of fix a Apple Computer. I have worked in an Apple Repair shop and I would not advocate anyone starting out to pry open a Powerbook or iBook for that manner. Way to many screws & as Pennstate points out could short something out.

Thanks for the heads up and the clarification ibook_steve.

Pennstate · 08:30 PM

Okay,

Let me clear some confusions. At least in my PB 12" 1.33ghz, the cpu was clearly meant to touch the copper heatpipes directly, while the other 2 chips uses a thicker purple pad. The thermal pasty material on the CPU was white. It may have been a pad, but there was no spacing between the copper pipes and the cpu. Therefore, Arctic sillver will work.

One more hint is to apply some AS on the heat pipe area above the CPU, rub it in, and then wipe it off.

It used to be that after 2 hours, the fan will kick in at full speed. But after the AS application, the fan only kicks in when I am using it to drive my dell 2007wfp lcd. I think if you can find a copper spacer that can bridge the gap between the GPU, chipset, and the heatsink, you'll get even better cooling. Right now, the GPU is consistently warmer than the CPU by 5C degrees.

Hmmmm... In fact, I will try to make a spacer out of folded aluminum foils for the GPU and the chipset the next time I open up my powerbook. And I'll take pictures this time.

Dr.Michael · Jun 8, 2006, 03:42 AM

Originally Posted by Pennstate

I think if you can find a copper spacer that can bridge the gap between the GPU, chipset, and the heatsink, you'll get even better cooling.

No question. Thermal paste is a bad heat conductor (compared to copper). It improves the situation only because it fills the gaps on the uneven ceramic surfaces and thus inreases the area of contact. This is why a thin layer is always better than a thick layer.

vacationgirl · Jun 8, 2006, 10:01 PM

So just the other day I took apart my 12" 1.33 PowerBook to replace a dying hard drive, and I had been thinking about replacing the purple thermal transfer pads with AS5 or some simiarl paste.

But for now, I didn't.

Now that I've got my machine running again with a new drive and fresh install of OS X, I've been using temperature monitor to graph my temps and I've noticed that although the CPU is cool enough (idles at around 46 degrees celsius, loads at about 55 degrees or less), it's the GPU that gets really hot. The GPU practically idles at 60 degrees!

Is there anything I can do to improve the GPU-heatsink connection? I noticed that there is a bit of GPU die peeking out from under the heatsink. I can see the purple pad too. Is there something I can do to replace the purple pads or improve the heat transfer from the GPU/chipset to the heatsink? If it's true that the heatsink doesn't fit snugly with the GPU/chipset, but does fit with the G4 CPU, what can I do? I can't apply paste to the GPU, right?

Any ideas on how to cool the GPU? A few months ago, I saw a CoreImage thread crash while I was using my computer. I think it might be because the GPU has been running hot. I'd really like to cool down the GPU.

I'm using a 12" PB 1.33 G4 model that was built in June/July 2004 and sold in August 2004, if that makes a difference.

So... what can I do to cool the GPU?

asodamiac · Jun 10, 2006, 04:38 PM

Interesting thread. My G4 powerbook gets really hot when using Photoshop CS2 to edit my photos. Don't know if I would open up my PB to apply the AS though.

asodamiac · Jun 10, 2006, 06:18 PM

BTW, I think as Mac users, we have been SPOILED when it comes down to fan noise. I'm sitting next to someone at the library right now, and she's using a Compaq laptop. This thing is ROARING and she said that that ROAR is normal. I can't imagine what it would sound like once it heats up (she also mentioned that her laptop will shut down when it over heats...). We're pretty fortunate to have quiet laptops, even when the fans are running

snoopy199 · Jun 10, 2006, 08:13 PM

I concur, I have an HP laptop for work, and the when its not in the port replicator, I hear the beast whine and roar - it is markedly cooler though, maybe I'd take a noiser mac if it meant not getting third degree burns on my lap.

Pennstate · 11:24 PM

Okay, I tried making a spacer out of folded aluminum foil (~36 sheets thick). But, I was not able to get good contact with the heatsink. Part of the problem is the the 4 ram chips are higher than the heatsink over the cpu core. After numberous tries, including cutting the spacer into a cross, I decided to go back to the thermal pad. But this time, I folded the original purple thermal pad in two. This gave the gpu better contact with the heatsink. I was able to lower the idle gpu temp from 58C to 53.5C.

SOmething else I did was to fold a sheet of aluminum foil into a very narrow strip and use it to fill the gap between the top edge of the heatsink and the case. I think this helped with the cooling.

No more mods for a while.

In battery mode only without an external display, and just browsing the internet, the GPU temp is 53.5, and cpu is 44C. Very acceptable.

Velocity211 · Jun 11, 2006, 12:04 AM

Which is better, the thermal pad, or the thermal paste. My GPU in my Powerbook is extremely hot. I saw pictures of the Powerbook open on iFixit and saw what looked like thermal pads on the GPU. Should I switch to the thermal paste if it helps reduce the heat?

Pennstate · Jun 11, 2006, 06:32 AM

Originally Posted by Velocity211

Which is better, the thermal pad, or the thermal paste. My GPU in my Powerbook is extremely hot. I saw pictures of the Powerbook open on iFixit and saw what looked like thermal pads on the GPU. Should I switch to the thermal paste if it helps reduce the heat?

The space between the GPU and the heatsink is too large for thermal paste. At least for the 12" 1.33ghz model, stick with the pad.