5 Replies Latest reply: Sep 6, 2013 2:58 PM by nikolaosinlight
theosib Level 1 (10 points)
There have been lots of discussion and rumors lately about the 2011 MBPs overheating. People hear about "excessive thermal paste" and assume that's the reason their computer seems hot. I've googled this. A number of individuals have reported that replacing their thermal paste with arctic silver and getting 10-degree reduction in temperature. Unfortunately, they don't always report whether that's in degrees C or F. On the other hand, a few professionals have investigated this issue and found much less significant improvements. The 2006 MBPs were purportedly the worst, yet changing the thermal paste didn't help much, and the latest models have lower TDP and better cooling.

Although Apple might possibly be able to use a marginally better thermal paste, this issue of it being "excessive" is probably a red herring. The heat sinks are pressed against the components with a huge amount of force. It doesn't matter how thinly or thickly you apply it -- nearly all of it is going to squish out from between the processor and the heat sink. The only possible problems would be if the excess were to get onto other components, interfering with their airflow, or over a period of years if the excess paste were to migrate around the machine and get into a place where it causes problems. As far as I have been able to determine, neither has been reported to happen.

One common reason for an apparently idle system to get hot is that it is not in fact idle. Spotlight indexing is a resource hog that uses significant CPU time. In fact, a number of users have reported that their brand new MBP was overly hot until they let spotlight run its course, which took a really long time, and then it was cool as a cucumber. Not everyone thinks to check to see what their computer is doing.

For those of you who feel that your Mac is overly hot when idle, wait until you find that the computer is hot, and open the "Activity Monitor" app. In the lower portion of the window, select the CPU tab, and in the upper right, be sure "All Processes" is selected. Watch it for a bit. Your computer may not actually be idle. (BTW, iStat misreports process names, so use Activity Monitor instead.) You've not personally commanded it to do anything compute-intensive, but MacOS X runs a lot of background processes like Time Machine and Spotlight that will run up your CPU temperature. This is completely normal.

For those of you who are finding the machine to be excessively hot +under heavy load+, you need to check your actual CPU temperature. I can't find the specs on the current Sandy Bridge, but in general maximum junction temperatures for Intel CPUs have ranged primarily from 90C to 100C. Use a tool like iStat to check your CPU temperature. If it's below 90C, then you're safe. The case may be hot, bur your computer is okay. If it increases above 90C, then I'd start to get nervous.

From personal experience, I can tell you that I damaged my 2007 MBP by running the CPUs at max for a protracted period. At the time, my MBP was the fastest computer I could get access to, and I was running vector-heavy code on both CPUs. For two weeks straight, the CPUs were at 90C. What I didn't realize was the CPU fans were not spinning at max RPM. If I had used one of the fan control utilities to fix that, damage might not have occurred. As it was, I later started getting kernel panics and such, which were solved by replacing the main memory sticks.

Since that time, the internal structure of the MBPs has changed so that the DRAM probably gets better airflow. But if you're going to do a lot of compute-intensive stuff, then here are three potentially useful pieces of advice:

(1) Install a fan control utility. Most tools let you set minimum fan speed. I prefer Lobotomo's Fan Control, which gives you more flexibility.
(2) Buy AppleCare. In theory, running the CPUs hot like that is within the design specs of the machine, but really, we're talking about notebooks here that prioritize portability over many other factors. Running them hot for long periods is pushing their limits, which has the potential to cause damage. Apple has a wonderful extended warranty. Use it.
(3) Consider using a desktop or server machine instead. Those have the luxury of having better internal airflow. They're designed for compute-intensive applications. Running 3D games on my old MBP makes it really hot, and the fans get loud. Running the same things on my iMac makes it slightly warm, and I can barely hear the fans.

Let me remind you that Apple is careful to describe these machines as "notebooks", not "laptops". As an engineer who has designed computer systems at various levels, I can tell you that price, performance, and convenience (e.g. weight and size) are a fine balancing act. If Apple were to design these machines to be a lot cooler, they would likely have to make them much more expensive, much less capable, or larger. Indeed, people posting in these forums are generally reporting the larger models (15" and 17") to be cooler than the 13". And you'll notice that the MacBook Air had to be significantly scaled back in performance to fit in that small enclosure without getting hot.

As a final word, although I think that Apple's quality control is better than the rumor mills would have you believe, there are going to be a small number of defective machines. If you've tried everything, and your computer is still too hot, then take it back to the Apple Store and politely ask for a repair or replacement. Apple Store employees are there to make Apple revenue, and the best way to do that is to keep the customers happy so that you'll by another Mac later, and your friends will buy Macs, and so forth.

Mac OS X (10.6.2)
  • GoTVols Level 2 (255 points)
    Very well written and very informative as well.
    Something to keep in mind before so many of us panic without knowing all the facts.
  • ajacks101 Level 1 (0 points)
    I just want to say to "theosib" THANK YOU for such an informative posting. Most of what you see these days in discussion/help forums is less on the helpful side and more on the flaming side.

    I really appreciate you taking the time to write all the information you provided. I learned a lot from it.
  • GoTVols Level 2 (255 points)
    how do you like your new MBP 2.2?
    Mine is on order, waiting for it to leave China.
  • theooriginal Level 1 (0 points)

    mmm, I have a MBP5,3 15" from year 2009, I believe?

    I get around 100C to 105C when I'm playing games on it, even with a laptop cooler fan...

    I am using iStats, Fan Control running on max fan speed and with a external laptop cooler fan

    I don't think it's normal at all...

    Any suggestions? I might just give the Arctic Silver reapplication a try...

  • nikolaosinlight Level 1 (0 points)

    I can't speak to the issues of the 2011 MBPs but I have a 17" early 2008 MBP that has been upgraded a fair bit... it has a 64GB Intel X25 Extreme SLC SSD as the primary drive and an MCE OptiBay enclosure has a Seagate 320GB 7200 RPM Barracuda drive... in addition it has an OWC 4GB + Apple 2GB stick to bring it up to its theoretical 6GB max (Apple max says 4GB).


    Unfortunately over the last few years I was continually having overheating issues to the point where the CPU and GPU would hit 81 degrees celcius and the system fans would spin up into high gear and it would shutdown.  If I was lucky and closed the lid as the fans were spinning up into high gear and waited a bit and opened the lid again then the system would not shutdown (but it would still remain hot).


    I would use smcFanControl and the fans would be running at around 4K - 6K almost all the time (even though I had the min configured around 2700 RPM).


    At first I thought the issue was related to the OWC 4GB stick but putting back the original 2GB sticks (for 4GB total) did nothing to alleviate the heat issues.


    Fast forward to late August 2013 when I decided to open the system up again and swap the 2nd HDD already in an MCE OptiBay with a 1TB version.  Again I was going with the Seagate but this time this was a SHD which has 8GB of NAND and the the drive was 5400 RPMs (my thinking was that yes its a slower drive but I wanted to eliminate heat issues altogether and this should produce less heat while the NAND helps somewhat speed wise - but the OS was already on the primary SSD and User folder was on the 2nd HDD so it wasn't as much a concern).


    I had also picked up some Arctic Silver MX paste for an $10 CAD (well worth getting as it is non-conductive vs. the cheaper version Artic Silver 5 which runs for $5 CAD... plus on what was about a $4.5K laptop and extra $5 isn't such a big deal) and was kind of reluctant to do a 32 step teardown as found on iFixIt.


    I had opened the system before a number of times but had never delved into opening the fans and giving them a good cleaning.  One of the reasons being that the left fan was not so easily accessible without removing more components (in the model version I had).  So I got both fans opened up and wasn't suprised to pull out fluff bunnies from the fans.  Though it wasn't as bad as I had expected.


    At this point I had a decision to make... stop and put everything back together... or delve in deeper and strip the system down to its bare metal... and replace the thermal paste.  Feeling a little lucky... and not for the faint of heart... I stripped it down and removed the motherboard.


    The first think I noticed is how rigid the paste was and how much excess paste there was.  I cleaned the CPU, GPU, etc... very carefully q-tips and 99% Isopropyl Alcohol (careful that the cheap kind can be anywhere up to 75% and isn't good to use).  I polished the heat sink metal with stainless steel cleaner and removed all the excess with a dry cloth (until no more polish would come off).


    I then proceeded to tin the CPU, GPU, etc... which supposedly reduces the burn in time of the thermal paste.  It wasn't clear to me initially what needed to be done.  So to be clear what I did was apply a very small amount of thermal paste on the heat sinks and using the side of a credit card spread it around the middle area.  Then using a clean cloth I rubbed the heat sinks until the paste was all but removed and all that was left was that the heat sinks appeared matte vs. shiny in finish (this allowed microscopic amounts of the paste to adhere to the heat sink thus improving the bond).


    I then applied small amounts of thermal paste to the CPUs and then used a piece of saran wrap to dab and smear it gently on the entire surface of the chips... making sure not to have more than a thin coat of thermal paste on the chips.


    I did all the 32 steps in reverse and after launching the system and getting the startup screen I thought I was good to go.  Once the system got running I'm not sure what compelled me to do so but figured let me reset the

    SMC and PRAM.  The latter made it impossible to boot my system until I booted using the OS X install disk and simply restarted my system from there.  I would say unless you "really" believe you need to never do a PRAM reset otherwise memories of windows blue screens of death may start flooding back on system boot.


    So what did I do to help my heat issue:


    1)  Put in a 5400 vs. 7200 RPM drive... but with NAND built-in... to trade off more speed for less heat


    2)  Cleaned out the fans and the thermal sinks and all other components (compressed air is your friend here)


    3)  Replaced the thermal paste with Arctic Silver MX


    What do I have to show for it...


    ... Quiet... fans simply however at 2700 RPM's (i.e. the min)... temperature of GPU is typically around 68 degrees and temperature of CPU is around 60 degrees... the system is so silent that I sometimes forget how loud it was when the fans would run higher or even speed up into high gear.


    What helped...


    ... all of the above IMHO... I don't thermal paste is a magic bullet... but then again I think 5 years with an OEM grade thermal paste is probably pushing it as it was quite rigid when I opened the system up...


    ... so what should you do... decide if its worth it and like the original OP consider the "OTHER" factors that could be contributing to your heat issues... because it may not be thermal paste alone... and as it is a large effort to get down into the heat sinks on MBP's I think its hard to get that data that is needed which would ideally entail doing everything but the thermal paste and seeing if the issue was solved and then doing the thermal paste and seeing the delta.


    Would I do it again...


    ... perhaps... but tread lightly as you are one mistep away from tossing your system... and IMHO I wouldn't even consider doing so if my system was still under Apple Care warranty...


    Hopefully this helps someone else out there grappling with a similar issue.