Apple OS X 10.5.7 overheats some Macs

Robert Black was right. OS X 10.5.7 adversely affects the internal heat management of some iMacs (and apparently also some MacBooks), causing the machines to overheat. Overheating, in turn, leads to such problems as freezes during iCal sync; freezes during iTunes sync; and the inability of attached hard drives to complete a backup.

Blah blah

I confirmed this by installing smcFanControl and watching my Mac get hotter and hotter as it tried to complete a SuperDuper backup. Disk Utility confirmed nothing was wrong with the attached drive. Swapping cables proved a faulty cable was not to blame for previous failed backups. Maddeningly, the backup got within 4GB of completion before locking up due to the overheating of my iMac.

Not every iMac or MacBook is affected. It probably varies by factory run and by model. (My MacBook Pro, for instance, is fine.) Third-party stuff and Migration vs. Tabula Rasa System Install seems to have no bearing on whether or not your Mac will choke on the update.

Since even running smcFanControl at settings recommended by Robert Black and others doesn’t cool the iMac enough to finish a backup or verify the quality of the attached drives, it may not make sense to replace my external hard drives (as new drives will likely also fail as the iMac overheats during backup).

With smcFanControl in place, I can use my iMacs but not back them up.

Apple needs to release an update that fixes the hardware problems this one created.

(And someone else needs to install it before I do.)

[tags]OSX10.5.7, bugs, Apple, Macintosh, update[/tags]

75 thoughts on “Apple OS X 10.5.7 overheats some Macs

  1. My maxed out (as of November) unibody 15″ macbook pro has been running hot since the update too. If I play any online video, the fans get going. Did this before, if I was using the better graphics processor, but not with the lower end processor. Now it does it using either one. Vimeo is unwatchable now too, constantly stuttering – but it was fine before the update.

  2. These 2.8 Ghz Intel Core 2 Duo iMacs (one for home, two for New York office) have always run hot. Always, always. But OS X 10.5.7 runs them hotter still—enough to destabilize them. The good news is, since installing smcFanControl and adjusting its settings, I seem to be able to run the home iMac without freezes or other disasters. (I just can’t back it up.)

  3. A bit desperate, but could you rig up a Heath Robinson-like external room fan, so it’s output was blowing into the bottom punched-grill of the iMac.

    With air being ‘pushed’ in, it may stay cooler for longer and allow a backup?

    Good luck.

  4. Argh! I have a 17″ Macbook Pro 2.33 GHz Core 2 Duo and over the last week or so it’s been running much, much hotter than normal. Since the OS/X 10.5.7 update in fact… Just opening Photoshop or watching a video on YouTube is enough to get the fans going. To date I haven’t experienced any freezing or crashes, aside from attempting to copy/paste a huge MySQL Export out of Firefox into BBEdit which was probably not a smart idea anyway. Apple, please fix this ASAP, I don’t want to have to buy a laptop cooler!

    Does anyone know if there’s any potential problems for the components and internals from running at these elevated temperatures?

  5. Man. Sour towards Mac all of a sudden Zeldman? Second post as of late warning of Mac issues.

    This one hits me closer to home, considering I’ve had heating issues with my MacBook and actually lost a hard drive to it. Might be my fault; I treat my MacBook horribly and upgraded to a HD that spins faster (therefore hotter) than manufacture default. I could understand heating issues with third party software. But there’s no excuse for iCal or iTunes. Regardless, I’d really like some numbers rather than having to decide what “many people” means to you.

    Any reports? Any studies? Any hard numbers pertaining to how many people are actually having these issues with their machines? I’m googling at the moment and I’ll reply if I find anything.

  6. Since updating to 10.5.7, my MBP is:
    -running super hot
    -my iPhone won’t sync with iTunes in the new OS, and
    -my laptop battery life sucks (the battery is less than a year old, and I’m just realizing that it’s really taken a nose dive since the update).

    Thanks for pointing out this issue.
    Mine is 2.33 GHz model, bought in Oct. ’06, fyi.

  7. @ dan lee:

    back off, fanboy!

    stop insinuating bad faith just cuz someone is pointing out the obvious: QA at apple is almost as bad as for the PC!

    the simple fact is that the web is crawling with complaints about this ridiculous over-beating!

    my mpb (c1d) is running at 100C! …and hangs.

    (I have also seen 10.5.7 repeatedly hang on an otherwise icey-cool mabook – but i surmise that the unibody case is such a great design that I suspect it’s external topside temp doesn’t closely reflect the CPU temp the way the previous chasis did).

    mitigating factors:

    * spring weather means an ample supply of cool air for favourable ambient conditions.

    * external room fan at close range seems to let the CPU run at 100C while the rest of the machine can disapate enough heat to prevent the CPU from choking.

    * running smcfan (thanx for the tip powerpage!) at full tilt (6000rpm) can knock off 20-40C from idle conditions (which provides cle
    enough extra head-room for the CPU at full utilization, again presuming it is clearing out the “easy” heat from the other components).

    * CPU utilization reduced by 20% when high-bandwidth USB peripherals (eg elgato turboHD) runs directly from mobo instead of through a (high-quality) hub!? – obviously anything that uses less CPU also uses less power.

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  9. You’re ABSOLUTELY right.

    After 10.5.7 upgrade, I was lucky to get 15 minutes out of my iMac 24″ before a complete freeze.

    I tried everything to fix it. Strangely, SafeBooting worked fine (no freezes) so I assumed there was an incompatible extension or startup somewhere. I spent three days juggling startups and extensions to NO avail.

    In near desperation, I tried Fan Control System Preference, setting it to the minimum upper and lower Temp Thresholds.

    I haven’t had a lockup since (over a week of very heavy use). The max temperature remains below 100 F / 38 C.

  10. No problems here, I have an iMac 2.66Ghz, the room ambient temperature is 13 degree’s Celsius and the highest temperature is 41 degree’s Celsius for the GPU diode. The most I’ve seen was getting close to 60 degree’s Celsius but that was when I was doing some video compression.

  11. Hi Jeffrey

    Wow… Glad something I said proved useful!

    If you’re not doing so already, try using Firewire 800 with your backups. At least the backup will go faster, meaning there’s a chance it will get to the end. Secondly, if you’re using SuperDuper (which I highly recommend), make your mirror backups ‘Smart Update’ backups, so it only copies what’s needed to make the volumes the same (the delta, if you will). That way, if your backup doesn’t finish, you can pretty much pickup where you left off when the machine’s cooled down.

    SuperDuper’s Smart Update is just that – smart. So it’s no worse than a full mirror backup. Make use of it.

    Good luck

  12. On my Macbook (new aluminum) fans running all the time after update, checked activity monitor and Safari 4 was taking 100% + of the CPU non stop. So, for me it appears that 5.7 and Safari 4 are having issues and Safari is causing the CPU to heat up. Also, noticed in the files open under the Activity Monitor that the flash plugins were loaded. That reminded me of the many complaints on the web regarding the mac version of flash…

  13. Hi Jeffrey

    BTW, my smcFanControl settings work for me, but you’ll need to experiment a little to see what works for you. Don’t be afraid to set the threashold higher for the CPU and HDD fans if you’re still overheating. Where I am it’s winter – where you are it’s summer. So your fans will probably have to work harder to keep the internals cool.

    Hopefully there’ll be a better fix before we change seasons again.

    Good luck!

  14. FEH! My MacBook Pro is now suffering because of the update as well. That’s three for three!


    1. Runs WAY hot
    2. As a result, shuts down and has a very hard time restarting. (Won’t wake from sleep. Appears dead.

    To bring it back to life I need to lean on the power button and sit through a boot sequence. Yuck!)

    Dang you, Apple!

    Have installed smcFanCcontrol on MacBook as well. Will see if it helps.

    James Katt said:

    Apple released an update for the temperature regulation firmware routines.

    Fantastic! Have you got a URL?

    Found via System Update. Installing. (Fingers crossed.)

    Secondly, if you’re using SuperDuper (which I highly recommend),

    Robert Black:


    1. SuperDuper! backup for Mac
    2. OS X 10.5.7 update: unsafe at any speed (Description of affected Macs being unable to finish backup via SuperDuper)
    3. Quick survey on OS X 10.5.7 bug triggers More about affected Macs being unable to finish backup via SuperDuper
  15. Zeldman, Have an update for those of us waiting to upgrade? Did the temperature regulation firmware work? (Thanks for discussing this. You posts are why I’ve held off updating my MBP.)

  16. Still wondering if the temperature regulation firmware worked? Care to share?

    After installing the firmware update, my MacBook Pro overheats and shuts itself down after sitting unused for a few hours. I can no longer wake it from sleep—I suppose because it no longer *goes* to sleep. It just overheats and shuts down.

    Aside from running way too hot and shutting itself down—two things it did not do before running the firmware update—my MacBook Pro is fine. There does not seem to be any software or hardware damage.

    Now let’s talk about the freeware software temperature control. After installing *that*, my home iMac runs fine (so far, knock wood), and my office iMac also runs fine (so far, knock wood).

    My office iMac can also once again make backups via SuperDuper and an attached HD after installing the freeware software temperature controller.

    Alas, my home machine still cannot run backups; my home HD appears to be defective. Whether OS X 10.5.7 brought about the HD’s problems or exascerbated previously existing problems that hadn’t yet surfaced … or whether it’s a coincidence, only an advanced technician and an Apple lawyer could say.

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  18. Check out this thread–the lockup/overheat seems to consistently on the second sleep that is started by closing the lid. It’s not a 100% effective solution for all that have tried, but it seems to work for most.

  19. Zeldman, Thanks for the update. I’m gonna hold off for OS X 10.5.8. I can’t risk my system being down for any period of time. Thanks again for blogging the problems you’ve experienced OS X 10.5.7. Hopefully, Apple resolves these issues quickly.

  20. Just a quick follow-up. I fixed mine based on the previous post, but by creating an additional interface of type “Ethernet”. Much suck, Apple.

  21. After updating to 10.5.7 before seeing this thread I’ve been experiencing much of the same issues. My software update doesn’t seem to list the “temperature regulation firmware routines” mentioned above. I’m using smc right now but would prefer an Apple fix. Is there any means of forcing this to appear in software update or anywhere else I can get it?

    I’m running on an early 2008 20″ 2.66ghz iMac with 4 GB of RAM and a 320 GB HDD.

    Very frustrating experience and the overheating seemed to affect the Windows side as well. I couldn’t boot into it at all after OS X started to continually freeze but when I let it sit and cool down for an hour I could get into both no problem.

    My question is: Do I have to do anything in Vista when I reinstall it to make sure that it also doesn’t overheat?

  22. I run “Fan Control” on my MacBook Pro, and smcFanControl on my iMac. I set the fan settings to keep the computers as cool as possible, even before the 10.5.7 upgrade. It just makes sense — cooler computers last longer.

  23. The only reason I worry about running the fan speed too high is that I’m concerned that it will shorten their life span. The default for the HDD appears to be at about 1200 RPM and since the 10.5.7 update I’ve had to run it at 3027 to keep it at a decent temperature.

  24. My G5 has shut down twice recently and now I realize the fan has been making more noise lately so I guess it is running hot. I find this totally bizare.
    Never had anything like this before. I am running 10.5.7.
    Is there a solution?

  25. I had the same problem on my pre-unibody 15″ MacBook Pro, until I installed the OS X 10.5.7 Combo Updater, which I read helped some people in the Apple Support Forums. After installing it, I left the MBP running with A/C adapter attached overnight, and it was just fine this morning. The machine has maintained a steady 112-114 degrees so far. Hope that helps others the way it helped me!

  26. Sadly, my computer is back to shutting down hard with no warning, despite installing the 10.5.7 Combo Updater. I’ve installed SMCFanControl 2.2.2, and my temperature has dropped from 120 degrees to 111 degrees, with the fans running at 4000 RPM. I really don’t want to run the fans that high all of the time, so will turn them down by a few hundred RPMs till I can find an acceptable speed that will keep the temps in that area.

  27. I’m so glad I found this site!!! I have been having problems with a used PB G4 I purchased. Thing has been crashing since I’ve been using it – which is after installing 10.5.7.

    I’m still playing with some of the tricks above to fix it.

    But I thought I would share one of my own.

    If you have a laptop that is overheating while you try to do some work…..try holding it in front of the air conditioner…..and working at the same time.

    I just happened to install mine on Sat. And and I was trying to reinstall the OS, the PB G4 kept freezing on me. So I decided to stand in front of the AC…..holding the laptop and installing the OS. That worked!!!

    Still getting crashing though! ARGH!!!

    Will keep you posted.

  28. My early 2008 white Macbook has these symptoms. After having made sure the update was installed correctly (reboot in Safe Mode, install via “10.5.7 Combo” file) I decided to try an “Archive and Install” with the OS X DVD to rollback the OS X version. I’ll then install the last known good update (10.5.6) and see how it goes…

    You’d think that if an all volunteer, open-source project like Debian Linux can find the resources to do proper regression testing of OS updates, that Apple could as well :/

  29. I noticed the same issue with my first gen macbook pro.
    After searching the interwebs I came across 2 subjects that helped resolving my heat/stability issue. The first one was to upgrade again from 10.5.6 to 10.5.7 by using the combo update and performing it in single user mode, and the second and most notable one was replacing the cooling past. Cleaning up the badly applied paste on the thermal conductor reduced the heat issue with 25%. Initially after applying the 10.5.7 patch and replacing the cooling paste the system stability still resulted in random shutdown while performing a Disk permission check, this disappeared after a reboot (the system seems stable now and comparing temperatures between 10.5.6 and 10.5.7 results in the same readings under similar load). End result, before the above procedure the CPU temp was some where around 90 and 120 degrees Celsius it now doesn’t get higher than 80 degrees while under heavy load. Hope this helps some one.

  30. As mentioned in this post or another, the Combo updater unfortunately did not fix the overheating problem on my Macs.

    I don’t know what you mean by this:

    replacing the cooling past. Cleaning up the badly applied paste on the thermal conductor reduced the heat issue with 25%.

    It sounds intriguing and important, but I don’t know what a “paste on [a] thermal conductor” is.

    Do you mean you opened the machine, unglued a piece of hardware, and re-glued it? Surely that is not what Apple expects owners of iMacs and MacBooks to do. Forgive my ignorance, I just don’t understand what you mean. Thanks!

  31. Hi Jeffrey,

    My excuses for not being clear.

    I was referring to the thermal cooling paste that gets applied to the heat sink that sits on top of the GPU and CPU (much the same as what you would do if you upgrade a CPU on a x86 system. (sorry for my bad choice in English words but I thought that’s the correct term to use).

    So I had to take apart my macbook pro in order to complete this procedure and it took about 1h to do so with the correct screw driver set . Mine is out of warranty any way and was quite desperate to get this heat issue resolved.

    Sorry to hear that your combo update didn’t fix it. I noticed a definite change between the live update (whish crashed) and the offline combo update. I have to mention that re applying the combo update on a failed 10.5.7 didn’t result in any improvements, I had to go back to 10.5.6 (I made a backup of 10.5.6 prior of upgrading to 10.5.7) and do the update.

    If the above would have failed on me I would have continued with cleaning out the system caches and performing an SMC reset.


    For more info on how OS X uses cache files and the boot procedure


  32. It’s frustrating that there has been no mention of a fix on Apple’s end. My iMac 2.66ghz (early 2008) is running smoothly for a while under smcfancontrol but I’ve noticed that my Vista partition is labouring no matter what the condition of the fans. This has me worried that overheating has caused damage to the hard drive.

  33. I’ve been holding off with installing the 10.5.7 on my aluminum iMac, but now we have 10.5.8 available.
    Does it change anything when it comes to overheating?
    Is the issue resolved?
    I don’t see spinning the fans harder a viable, long-term solution.

  34. @shadow:

    Don’t know if 10.5.8 quietly solves the overheating issue. Will find out soon. I’ve installed 10.5.8 on one machine, my home iMac, with no problems so far after several days’ use. (I repaired disk permissions and cleared caches immediately after installing via Cocktail in “Pilot” mode.) The Mac feels slightly peppier after the update, but that could be the coffee talking.

    Of the three Macs affected by 10.5.7-itis, the MacBook Pro laptop was worst hurt. It still shuts itself down constantly after overheating. I can never just wake it from sleep. I always have to hard-wake it by leaning on the power button. MacBooks are famous for overheating, but this one did not do so until I installed 10.5.7. Now that I’ve installed 10.5.8 on the home iMac with no trouble, I’ll install it on the laptop next.

    If the overheating and unwanted power-down issue improves, I’ll shut off smcFanControl (or neuter it) and see what happens. Keep watching the skies.

  35. Jeffrey,

    Thanks a TON for posting/blogging about this issue. While my black MacBook was never as affected as your MacBook Pro, it’s definitely run a lot hotter with 10.5.7.

    I’m installing 10.5.8 this weekend, and hope to see the same results you’ve had!


  36. Jeffery,

    Thanks for the post,
    As I am new to using Mac in general, I have had my Macbook for about a month or so. I do find that it gets warmer than a PC in general, but I have had no problems with it over-heating as of yet.

    Its kind of a pain when computers act up.. I know.

    Good luck.

  37. Glad you’ve been watching this. I’ll try the update and hopefully cut the cord between my AC window unit and the back of my Mac.

  38. Jeff, I’ve had great success with undervolting my 2.33Ghz Core 2 Duo 15″ MacBook Pro by using CookBookController.

    What it does is allow you to test for stable voltages lower than the defaults for your computer’s various speed steps. Instead of running at 1.18v at 2.33GHz, this allows you to set it to something lower. Lower voltage = lower temperatures and longer battery life. I have been able to drop mine to 1.0875v at full throttle.

    It’s not free at $10, but is one of the best ways I’ve spent $10 on my Mac:

  39. Thanks, folks!

    Good news, so far.

    On the second day after installing 10.5.8 on the laptop, it no longer overheats and shuts down.

    I can go to the MacBook and click its keyboard and it wakes from sleep, like a viable Macintosh computer, instead of like a dying thing.

    It’s too early to be sure that 10.5.8 fixed what 10.5.7 so painfully broke. In another week, if the laptop still wakes normally from sleep, I’ll conclude that 10.5.8 does indeed fix the severe overheating problem that 10.5.7 introduced.

    Watch this space.

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