Level 1

0 points

Thermal compound replacement, RESULTS and PICTURES

YOU CAN HAVE A MACBOOK PRO THAT ISN'T SCORCHING HOT!!
(note that this will NOT fix any whine or moo; they are unrelated problems)

Here's how.

My Mother's Macbook Pro (Or Cookbook, if you will) Arrived a week ago today. I played around with it to make sure everything is alright because my mother doesn't know how to check for things like dead pixels, bad ram, or cough improperly applied thermal compound.

One of the first things I noticed after turning on the new MBP is how totally sweet it is! The second thing I noticed is how freaking hot it is: I recoiled in pain from the Fn key bar the first time I touched it. Disappointed, I started searching the web and sure enough, pretty much everyone who owns one is complaining that it's too hot for comfortable use.

Apple calling this a "notebook" instead of a "laptop" is a total semantic cop-out. It's a PORTABLE COMPUTER and I must be able to trust it around my dogs, children, valuables without the MagSafe burning up or the battery swelling and bursting.

I don't have objective figures for just how hot it was, but it was right about at my pain threshold above and below the belt, and sometimes over it. I couldn't hold my hand to it for more than a few seconds. In particular the area to the left of the touchpad was of concern. I do have before-and-after figures of the CPU and HDD; I invite yourselves to look at them:

Before After (Temps in degrees C, ambient 25 C)
50-60 26-35 CPU (idle)
76-85 56-65 CPU (load)
41 33 HDD

In particular the HDD figures are a great relief. HDDs are notoriously sensitive to temperature and even a few degrees C can cut their lifetimes significantly. Furthermore the area is now cool to the touch and I can once again rest my left palm on it without discomfort. The ranges are due to the fact that the sensor inside the core duo is flaky. In 5 seconds it can run anywhere from +-5 to +-10. Nevertheless it is accurate enough for our purposes. Below are photos, procedure, and a rough outline of test methodologies:

http://www.pbase.com/silentplummet/image/62641589

Here's the idle scenario before the procedure. The computer has been on for hours (days really) and I'm doing the work I normally do on it. TextEdit is open (to a little project I'm working on) with firefox and the temperature monitor. Alt-tab is to show that those are the only programs running. CPU temp is dead at 50 C. This is INSANE for an idle figure on ANY computer; desktop, laptop, "notebook" or otherwise.

http://www.pbase.com/silentplummet/image/62641590

The operation area and stress test. To stress the ATI chip I've jacked up the resolution, run a couple of quartz programs, SNES9x (a hardware emulator; the software shown is called "Energy Breaker") with a brutal multitasking OpenGL hardware renderer, and Google Earth. To get the CPU going I have Adobe's Lightroom processing thumbnails, and again SNES9x. For various I/O I have two shells executing yes > /dev/null, a USB mouse plugged in, and all the HDD access from lightroom. I figure it paints a pretty good picture of the "worst case scenario" of hardware stress for a laptop like this.

http://www.pbase.com/silentplummet/image/62641591

The CPU core(s) is at 76 C. I should note that at this point, as hot as the CPU is, overall the case is really not much hotter than it was before. In other words, it's just as unacceptable.

At this point I turned her off and dug in. I used a howto from Ifixit to serve as my guide. The procedure went without surprises until I got all the way to the logic board.

http://www.pbase.com/silentplummet/image/62641592

Dear lord!! That is an obscene amount of compound. It's casting a shadow over the rest of the board!! This gray gak is piled on so thick, it's no wonder the cooling system couldn't work effectively. It had even gotten all over components nowhere near the dies. That definitely cannot be good for their lifespan. Here's a shot of the heatpipe:

http://www.pbase.com/silentplummet/image/62641593

Terrible. Thermal compound has been squished out all over the place, including the chassis itself. This explains why it was getting so hot. A photo from the MBP service manual has been floating around the net, illustrating that this gross amount of compound is actually according to procedure.

http://www.pbase.com/silentplummet/image/62641594

Clean as a whistle. After removing the bulk of the compound with q-tips I used ArctiClean 2-step process to emulsify the rest and remove it with paper towels. You can see it's not perfect but it's close enough for me. I'm not overclocking this thing; I just want to run it "in spec" and have it not burn me. At this point, the CPU dies and the heat pipe interfaces should have mirror finishes. It's an overclocker's dream, and Apple already did the work for me.

http://www.pbase.com/silentplummet/image/62641595

This is how I applied Arctic Silver 5 to replace the compound I removed. Squeeze the tiniest little bit out of the syringe directly on to the die, and scrape it across with a flat edge (they recommend a razor blade but I just used a plastic ID card). Take the amount of compound you see on the Core Duo (on the right) and make a flat, even layer like the one you see on the ATI (left).

http://www.pbase.com/silentplummet/image/62641596

Turned it on and went straight for the hard stress test, after making sure everything was OK of course =) Wow! It reads 58 C in the screenshot, and doesn't go above 65C!! Moreover, there isn't even a bit of warmth above the Fn keys, and the HDD area is cool to the touch. I'd call this one a complete success. I'm idling right now and the temperature reads between 26 and 31C. Even the bottom is just slightly warm to the touch. Now I have a real laptop again!

So why did this happen?

There's a lot of confusion about the way the Macbook Pro cools itself. I admit it's confusing. Basically, Apple is shipping Macbook Pros with one cooling system, and replacing the thermal compound changes it into a very different system. Let me try to explain what I learned from digging around the hardware.

1. The built-in thermometer in the CPU is flaky. That's why you have to access it with a kernel extension and all kinds of hacks, and why Apple circumvented it completely in the cooling system. That's right: the MBP cooling system ignores the Core Duo temperature entirely.

2. The cooling system consists of a convective (my guess, I don't think anyone really knows what kind of) heatpipe which is in the base, directing heat out to two heatsinks which are then to be cooled by two fans if need be.

3. There are two temperature sensors. One is on the heatpipe itself, and the other one is on the chassis just next to the right fan. Probably the hardware monitors these temperatures and the differential between them to decide when to activate the fans and how long.

4. Behavior before the replacement procedure: The CPU core would get hot, hotter than I've ever seen a CPU go, at 80-85C. Most people confirm their MBPs also exhibit this. Where was this heat going? Well the fans didn't turn on until I put it at full load. Even when the fans did turn on, there wasn't much warm exhaust coming out of the vents at the back. The chassis heated up until it was unbearable, and most of the excess heat was being radiated away from it.

To sum up, the ineffective thermal interface between the CPU dies and the heat pipe was inhibiting heat from tripping the fan sensors. This explains why the fans didn't turn on until drastic temperatures were attained, and why the chassis got so hot. Essentially, the chassis was serving as a big heatsink for the CPU, which is the only reason it didn't overheat and shut down.

Effective, Apple, but not quite appropriate.

5. Behavior after the replacement procedure: The first thing you notice is that the fans scream from the second you turn the thing on. They aren't going full blast but pretty close to it. An effective thermal interface using an APPROPRIATE AMOUNT of AS5 (anything would do but I figured if I'm applying thermal compound, why not go for the authority) allows the heat to go straight from the cores into the heatpipe, tripping the sensor early and fast. The fans come on, I can feel hot air coming out the back, and the chassis now removed from the thermal equation is cool and comfortable again.

Of course, the thermal equation is different from before, and from the way Apple has tuned the fans to work from the factory configuration. This is more cooling than we probably need, and I foresee an update to Tiger allowing us to choose the thermal/noise tradeoff for ourselves.

Well, I hope that explains it, and I hope that those of you still suffering the abuses of your "in spec" MBP can take some hope from my findings, or are emboldened to go ahead and repeat the procedure yourself. I will post informative links here.

http://www.ifixit.com/Guide/85.1.0.html
http://www.arcticsilver.com/
http://forums.somethingawful.com/showthread.php?s=&threadid=1864582 (This is where I learned of the thermal paste issue)

Remember if you ever open up your MBP to NOT BREAK ANYTHING and please, always read the instructions before you reach in. =)

Mac mini, Mac OS X (10.4.6)

Posted on Jun 28, 2006 7:34 PM

34 replies

Jun 29, 2006 2:34 AM in response to Christian Winter

Thanks for the good read.

Jun 29, 2006 3:52 AM in response to methanol

When I replaced the thermal paste on my first MBP, the CPU shot up to over 100C but the casing was cool to the touch. Before that the CPU peaked at 79C and the casing was scorching. Explain that one then.

DrPlokta

Level 1

25 points

Jun 29, 2006 4:11 AM in response to thefunkymunky

Most likely the thermal paste was installed poorly and wasn't conducting much heat away from the CPU into the heat pipe, so the CPU got very hot but the machine stayed cool as the heat wasn't being conducted properly from the CPU into the machine.

Jun 29, 2006 4:16 AM in response to DrPlokta

OK thanks. I'm pretty sure I applied it correctly, following the pictures online and the info on the Artic Silver site. I'm debating whether or not to do the same on my new replacement MBP. Under load the machine doesnt rise about 80C and thats when its lying on my bed. The casing is hot though.

Jun 29, 2006 4:28 AM in response to thefunkymunky

They let you replace it after the mod? O_O
Did you get to ask any of the Apple tech people about the heat?

Jun 29, 2006 4:32 AM in response to Sarkastik

They let you replace it after the mod? O_O
Did you get to ask any of the Apple tech people about
the heat?

The had to replace the machine as they damaged it when it came back from AppleCare (it went in just to replace the screen inverter). I wasnt happy and complained...a lot! So they replaced it with a new machine. Well, a Week 14 (I had a Week 7 previously) but it was brand new, just older stock.

cal6n

Level 2

265 points

Jun 29, 2006 4:59 AM in response to Christian Winter

That article is utterly irrelevant and has been torn apart many times, although it does at least show the result of forgetting to reattach a sensor lead. The author complains of heat, fixes his grease and then compares his computer's temperatures with another machine entirely, proving nothing! It has become apparent that some machines suffer, while others are fine. The second machine is obviously one of the latter

If you have one that is fine (temps 55-57C idle; load temp peaking 80-82C and settling at 75-77C and bearable case temperatures) then lucky you. Others aren't so lucky and surgery is required. Some owners even report that the cores heat up enough to trip the safety features built into the core duo (at 100C) and cut the clock speed to prevent themselves frying! It must be said that in extreme cases like this, Applecare should sort it out.

Methanol, it really does sound like you've a sensor wire loose in there. They are keyed like most internal electronics connectors and should only reassemble one way. Your temperatures are suspiciously low and you should only hear your fans ramp up to speed after a minute or so of full load, settling down to being quiet but audible after a couple more minutes. Upon removing full load, the fans should become inaudible almost immediately.

As one of the early "Greasers" (the first was a guy called Jean-Cyril on these forums) I've stopped trying to explain to the nay-sayers, Apple apologists and armchair engineers who remain firmly in denial that there is a problem with some MBP 15" models and that it is solvable by the correct application of thermal compound. The bottom line is that many owners of the "cookbook pro" have proven to themselves that this procedure works and now are able to confidently and comfortably use their machines at high load for long periods of time.

As far as the warranty is concerned, it will not be invalidated unless you actually damage something while you are working inside your computer. This is a point of consumer law and not a matter of opinion. Even so, it must be stressed that no one should even think about attempting this procedure unless they have the appropriate quality tools; are experienced in this type of work and are confident in their ability.

Jun 29, 2006 5:17 AM in response to methanol

Hi methanol. I too have reapplied the paste on my MBP a couple of months ago, and I experienced a significant drop in CPU temp - although not as low as the figures you report, but some 15 C lower than they used to be. And like yourself, I don't care much about the chip temperatures; what's more important is that the fans actually work now. Most of the time they spin inaudibly but they react quickly to moderate CPU/GPU load, keeping the entire case and components cool even at high loads for an extended period of time.

You should realize however, that wherever you post this story, there will always be people (with whatever agenda) who will argue that The Heat is not caused by the oreo-like thermal paste job, or even that it's within spec gasp. For example I got in an argument on osnews.com (which got rather vicious btw) where someone insisted that it was caused by a design flaw and not the paste, while I know for a fact that the MBP is very efficient at dissipating heat. After all, I always use the thing on my lap. If I wanted a desktop PC I'd have bought an iMac, right? Anyway and IMO, you just added a couple of years to the life of the logic board of that MBP. Now all you have to worry about is a busted fan. Which are 30 bucks and take 30 minutes to replace. Peace of mind indeed. Your Mom will enjoy this thing for years to come.

Ps, don't bother checking for loose thermal sensor connections. If you forgot to insert them you'd notice it for sure. The fans would run at full blast ALWAYS. That macdevcenter article is linked to way to much if you ask me.

Natsus

Level 1

55 points

Jun 29, 2006 5:23 AM in response to Bill DeVille

great post, but this is untrue. I have personally done the mod and my notebook is still as quiet as ever. The only difference however is that the fans actually turn on at 55c-60c. It isn't a case of a detached thermal sensor because if that were so, the fans would be on at 100% all the time. My drop in temps however were significant. On a full load, it dropped 15c (85c to 60c)

You're right however, I still would NOT recommend this. Why? Because replacing the thermal grease does not guarantee your notebook to run cooler. There was another thread like this, and it looks like only a small percentage of those who did the mod had results similar to mine. Everyone else either didn't work at all, or had a small decrease in temps (2c-3c).

Natsus

Level 1

55 points

Jun 29, 2006 5:33 AM in response to chambone01

chances are, the notebook will die long before the fan. Fans are rated to run at full speed for at MINIMUM 10,000 hrs. That's 416 days of having that fan spinning constantly at max speed.

Jun 29, 2006 5:47 AM in response to Natsus

True. In theory it should take ten years to burn one out with normal use.

Jun 29, 2006 6:49 AM in response to Bill DeVille

Ok no offense but could you give us some links, refrences to the technical literature? You've mentioned it a couple times through out posts. I want to read other opinions. 🙂

What confuses me is why would Apple do something like this if it were so bad? Then again how to explain the huge drop in temperature after reapplication of paste?

So I asked my dad (he's an engineer) and he was disturbed by the fact that so much paste was used, and what a waste.
Yet...he then said it shouldn't really make too much difference either way (note: he mentioned he couldn't make a proper assesment about the issue without looking into it further. I just explained a little and showed him the pics of the before and after of thermal paste application).

So now I'm really confused. I wish more people who don't have the problem would say something 😀

methanol Author

Level 1

0 points

Jun 29, 2006 8:57 PM in response to methanol

UPDATE

Thanks guys, for all your support. Including you, DeVille, for your excellent Devil's Advocate. I've become able to articulate and understand the subject more clearly because of it.

Unfortunately... I cracked into my laptop again today, no less than three times. I will discuss my findings here.

1. This morning, the laptop ran as I left it last night. The fans go loud and the thing is blissfully cool. Some very helpful and awesome posters in this thread noted that I may have left a thermal sensor wire undone, a distinct possibility, into which I decided to check.

2. I cracked my MBP open again and poked around. Unfortunately one of the thermal sensors attaches to the bottom side of the *@#% logic board so I had to take it out just to be sure. Well, as I had thought, they were both connected! I wiggled them and gave a little extra pressure just to be certain. I replaced the logic board and sutured her up. Upon booting, the fans behaved more "normally" and thermally, things looked strangely (and disappointingly) like they did before I ever messed around. 50-55C idle temps again and a chassis hotter than Angelina Jolie.

A few hours running like this, I started up Google Earth. Mac OS X crashed after a few seconds. Something was wrong.

I considered the possible causes. Apple Hardware Test reported no problems. Did messing with the thermal sensors change anything? Nah, AHT said no problems and they were both connected anyway. Could I have applied the compound wrong? Nah, it was cool as ice before I messed with it. Might I have destroyed the even interface by removing and replacing the logic board?

3. I dove in again, determined that the 6th time would be the last time. I painstakingly cleaned and reapplied thermal compound. I meticulously checked, double checked, and triple checked the thermal sensors. Closed her up, went straight into AHT. No problems, but the fans were running full speed again. I'm now back where I was at #1. Cool as ice MBP and stable, but the fans run constantly.

Can someone help me make sense of this? The only thing I can think of is that the temperatures are so LOW that the sensors bug out and the system goes into save-the-ship mode. It seems unreasonable that Apple would do this but is it possible?

The The

Level 1

15 points

Jun 29, 2006 9:40 PM in response to methanol

I think one problem is that you meddled with it. Every time I obsess over something and start meddling with its constituent parts, I end up ruining it, or at the very least causing some sort of irreversible, unfortunate damage. This is why I'm as reluctant to open up the MBP and replace the thermal compound as I would be reluctant to father Courtney Love's children. It's a tedious task whose outcome would plague me for years to come.

methanol Author

Level 1

0 points

Jun 29, 2006 10:22 PM in response to The The

This is neither informative nor helpful. I've been working with computer hardware on a daily basis since I was 9 years old in 1994. I know basically what I'm doing by now. Furthermore it stands to reason that had I messed something up by my "meddling" it would be at the micro level, e.g. ruined one of the zillions of electrical traces on the logic board with a stray screwdriver head, or broken a lead off the PCB by over-flexing it. Not to mention spontaneous discharge of built up static. But I am very careful about these things and my hardware works 100% fine.

I'm sorry you break things when you touch them but the inside of a computer, even a Macbook, is not some pristine magicland filled with the mysteries of the universe, unsullied by the touch of men.

I asked a very general question, I know, but it was on a very specific topic: 'what is the shizzle with my fans'. Is there any information I don't know about the thermal monitoring/fan system? Let further replies address that topic.

Edit:

Specific questions I would like answered:
1. Is a disconnected thermal lead the only cause for the fans to default to full blast? If there are other causes, what are they?

2. If there is an issue with the cooling system, does Apple Hardware Test either test or report it? It cycles both the fans on and off individually, even after the mod, but if a thermal lead were disconnected would it report such?

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

Thermal compound replacement, RESULTS and PICTURES