kernel panics and macbook 4.1 running hot

Discussion in 'MacBook' started by drjaymez, Jul 10, 2010.

  1. drjaymez macrumors member

    Sep 27, 2008
    I have been having issues with my 2008 white macbook. It is a core2duo 2.4 Ghz. Running 10.6.4. I have upgraded the HD to 500GB and memory to 6GB.

    I started having random lockups 5-6 mos ago. Kenrel panics telling me to reboot. "unlocking an unlocked mutex" I noticed hard disk corruption associated with these, that I can repair with disk utility, but they recur with future panics.

    SMART reporting on the HD shows no problems, and I even checked the thorough report in ubuntu with no bad sectors or read/write errors. memtest86 runs all night with no troubles. Today while troubleshooting I noticed that my CPU temps are high. idle temps are in the mid 60s centigrade. When I run "yes > /dev/null" in two separte consoles, my temps spike to 105 C. I feel like this is a problem, and potentially the reason for my kernel panics.

    I am planning to dismantle the macbook and clean the fan, which my hardware monitor shows runs at 6200RPM max (which I believe is appropriate, but I bet it is dusty!). I have two questions:

    1. Is this a probable cause of my problem?

    2. Should I also reseat the heatsink while I am in there and put higher quality thermal compound like Arctic Silver on it?

  2. Pax macrumors 6502a

    Dec 12, 2003
    These temps are pretty normal for a pre-unibody Macbook. If you search around here (use MRoogle) you'll see lots of temperature threads. Make sure you are looking at pre-unibody models, they tend to run hotter than unibodies.

    Apple always seems to design its cooling system to allow the CPU to reach its Intel defined maximum (105 C for your CPU) for just a minute or so before the fan brings it down to a more sensible temperature.

    So your CPU temps may be a red herring - they are not unusual. Is there a connection between high temperatures and kernel panics?

    IIRC with these models high temps can cause problems with memory. Check out your memory temperatures if iStat reports it. Try reseating your memory. You have to press those sticks in HARD. It may be that the thermal expansion/contraction can make the contacts move slightly.
  3. drjaymez thread starter macrumors member

    Sep 27, 2008
    Thx for the reply. I am beginning to think the temps may indeed be a red herring. I had another kernel panic while doing mundane tasks with the temps low and the fan manually set to max. Memory temps usually run in the mid 40s.

    Is there any benefit to reinstalling the mac OS, is if it were a Windows machine acting up?

    Also considering removing one stick of memory at a time and seeing if I still get errors, but running for days with 2GB of RAM doesn't sound like fun. I think it was reassuring that I didn't get errors with memtest, though.

    Other thoughts?
  4. Pax macrumors 6502a

    Dec 12, 2003
    I am told (I am not an expert) that RAM problems are the most common cause of kernel panics. I would guess that the fact memtest is OK might not be conclusive, because the panic might be caused by intermittent disconnect of the RAM module.

    I think the idea is that oxidisation on the 100+ pads can cause an occasional disconnect between RAM and logic board. Thermal expansion/contraction might exacerbate this.

    I would take both RAM sticks right out of the machine, look at the contact pads and check they are fairly clean, then reseat them. Try that for a few days. If no joy you might want to try running with 2 GB for a while - you might have to suffer! (hey, I run 2GB all the time, including running Parallels VMs - what a cheapskate I am!!)

    Reinstalling Mac OS? I guess it can't hurt though it would be tedious. You might want to post in the OS X forum and ask there. I'm not a software guru.

    It sounds to me like memory is your best bet. Try using MRoogle. it's helpful.
  5. drjaymez thread starter macrumors member

    Sep 27, 2008
    Thx. Definitely have been doing my MRoogle homework.
    I have not had bad RAM that memtest has missed before, but I have certainly heard that it is possible. i will try reseating the memory as suggested as well. Then running with one stick or the other for a few weeks at a time should help me figure out if that is really the cause. Sounds like I could also uninstall 3rd party software, although I mostly have mainstream things. Will keep you all posted.
  6. LXguy macrumors newbie

    Oct 28, 2008
    Does the memory install coincide with the kernel panics? Have any external hardware plugged in on a regular basis?

    I'd try running with just the 4GB stick and see what that gets you.

    Theoretically its the more likely of the two to have problems (lots more points of failure), so if its the RAM, I'd think your crashing would go up if it were the culprit. Of course, if it goes away entirely you know the 2GB is the problem.

    Lots of the video cards on these machines are not-so-hot either. If you're out-of-warranty a test can be expensive, but I've seen a lot of machines have recurring crashes because of video card issues.

    Good luck with it.
  7. drjaymez thread starter macrumors member

    Sep 27, 2008
    I know I never had a kernel panic when I had 2GB (1x2). When I went to 4GB (2x2) I may have had a kernel panic or two. Now that you mention it, I do believe it has been more common since I switched to 6GB. I do have an external software striped RAID0 2 bay firewire enclosure. But I have had kernel panics without any external hardware attached.

    Currently running just the 4GB stick and Running Rember continuously. Will see if I get any troubles over the next few days.
  8. advres Guest


    Oct 3, 2003
    Do you have a disk in your optical drive? In an old powerbook I had back in the day I was getting continued kernel panics. It was from a failing superdrive that would randomly spin up when a disk was left in and would cause a kernel panic. I am not techie when it comes to the internal stuff so I dunno, that is just what the tech said when they replaced my superdrive. Never had a kernel panic on THAT machine again and I had it for 4 more years.
  9. johnnyham macrumors regular

    Jun 18, 2010
    The old Macbooks weren't designed to run with any more than 4 GB of RAM; see Apple's support page. This could be the cause of your kernel panics.

    Also, 105ºC is a VERY dangerous temperature for your computer. That's 221ºF. You could boil water on your CPU. The max temperature that it should reach under normal operating conditions is around 74ºC or 165ºF.
  10. Pax macrumors 6502a

    Dec 12, 2003
    Then we are all SOL :). Lots of Macs made in the last 2-3 years (I suspect all of them) seem to reach about 105 C when the CPU is torture tested. That's the Intel Tj,max spec limit for C2D processors (with one early model exception which had 95 C).

    Look around on these fora, there are loads of people reporting 105 C. Mine does it, others I've seen with my own eyes, others reported on here.

    I assume since Apple has made, what, 10 of million plus computers like this, it's pretty convinced that 105 C is not "very dangerous".

    And what has water got to do with it? Last time I looked my CPU wasn't made of water. The CPUs in your car reach 140 C, maybe 150 C. The exhaust valves in your car reach several hundred C "hot enough to melt lead". So what?

    Yes I know this will start a huge flame war about whether heat damages components. But re the OP's problem, his Mac is showing temperatures exactly the same as millions of other Macs. Telling him his temperatures are "very dangerous" is IMHO unhelpful and probably incorrect.
  11. drjaymez thread starter macrumors member

    Sep 27, 2008
    I think if I don't get kernel panics with either 4GB or 2GB I will be forced to admit that this may be the case, esp. if I go back to 6GB and get them again. That said, there are plenty of people on this forum running 6GB in these machines.

    I'm obviously concerned about these temps. I'm not thrilled about intermittently running the CPU at those temps. I wouldn't tolerate it if it was my home-built winbox. I think at some point I will likely open her up, clean out the fan, and reseat the CPU heatsink, but I guess my question is more related to whether or not this is the cause of the kernel panics, and given that I haven't been able to reproduce one with max CPU usage alone and fairly impressive temps leads me to believe that it is not the cause of my current problem.

    Thanks for the ongoing assistance, all. The macbook has been running like a dream on 4GB of memory for the last 24 hours. Left it running Rember and two instances of yes > /dev/null overnight. CPU temp 84C this morning. Memory temp 59C. May try the next 24 hours on 2GB and see.

    Regarding the GPU, downloaded Steam and will play something intense 3D to test.

    I'm a little annoyed that iStat can't log temps.
  12. drjaymez thread starter macrumors member

    Sep 27, 2008
    hmm half-life 2 kernel panics like it is going out of style. half-life 2 isn't exactly proven mac software. Going to try doom3 demo and if that has the same issues, going to try the other memory stick.
  13. drjaymez thread starter macrumors member

    Sep 27, 2008
    Played doom3 in a window. CPU temp 70 and GPU temp 54. No troubles at all.
  14. drjaymez thread starter macrumors member

    Sep 27, 2008
    Played Doom3 for about an hour full screen. No troubles. Ugh.
  15. Pax macrumors 6502a

    Dec 12, 2003
    That sounds odd. I've seen Steam games crash (eg Portal) but not KP.

    If you can reproduce your KPs with HL2 that sounds like a really productive area to pursue. Great idea to swap the RAM stick.

    I'd suggest posting re HL2 KPs on the OS X forum. The geeks over there might ask you to post some crash logs or whatever. They are pretty good at diagnosing that kind of thing. They should at least be able to tell you whether it's HW or SW.

    I think games tend not to max out the CPU temps like our torture tests do. I guess there is enough i/o from memory and the disk to keep the CPU well below its thermal design power. To really max out CPU and GPU you could play Doom3 and run a yes > /dev/null to really get things cooking???
  16. drjaymez thread starter macrumors member

    Sep 27, 2008
    ugh. HL2 was only a partial download (99% complete). Why would it even try to run a partial download? I don't game much, but Steam doesn't seem ready for prime time. Now re-downloading and will see if I still get KPs.

    I may check in with the OSX folks. Not a bad idea.
  17. drjaymez thread starter macrumors member

    Sep 27, 2008
    Got iPhoto to crash with the 2GB of memory. No KPs though.
  18. Pax macrumors 6502a

    Dec 12, 2003
    Crashing is easy, KPing is hard! iPhoto crashes for me too, not often but occasionally. But I haven't seen a KP in ages. I don't think I've had one on this MBP which I've had for about 8 months.
  19. drjaymez thread starter macrumors member

    Sep 27, 2008
    Got sick of troubleshooting and fell back on a tried and true Windows trick. I wiped the HD and did a fresh install of Snow Leopard and my apps. Now migrating back over my iphoto library, iTunes library, etc. No KPs yet. I have the 6GB memory back in since I felt like with all the hardware testing I had done I hadn't found a reproducible problem. If this solves the problem it was software, and if not, I'm not sure what I'll do. Perhaps with upgrade to Snow leopard and all the 3rd party apps, there was a file that wasn't quite right.
  20. Pax macrumors 6502a

    Dec 12, 2003
    ah, c'mon, that's cheating :)
    no, seriously, that's a good idea. A fairly tedious exercise I am guessing. hopefully it'll fix it.
  21. drjaymez thread starter macrumors member

    Sep 27, 2008
    So much easier than on a windows box! Reinstall took about a half hour. Downloaded updates. Added Open Office, VLC, Handbrake, and reinstalled iLife. Copying stuff over from my firewire backup has been a piece of cake.

    Will report back.
  22. johnnyham macrumors regular

    Jun 18, 2010
    I don't mean to insult your intelligence or anything, but I think you have Celsius and Fahrenheit confused. 105ºC = 221ºF. When using Flash with Mail, Safari, iTunes, VLC, TextEdit and various background apps open, I peak at about 72ºC or 162ºF - I have a mid-2009 Macbook. Looking around on the forums, I see reported temperatures of 40-70ºF for pre-unibody Macbooks. If the OP meant to type 105F rather than C, then I retract my previous statement and say that it's normal.

    The reference to water was merely used as a comparison. Remember the jokes about how the Macbook Pro got so hot that you could cook an egg on it? Egg whites coagulate around 65ºC - and this was the hottest those Pros got apparently.
  23. Pax macrumors 6502a

    Dec 12, 2003
    No, I said C and meant C. Perhaps you or the other posters have got it the wrong way round.

    "I see reported temperatures of 40-70ºF for pre-unibody Macbooks"

    Can you link me to one, I would be curious. Given that typical room temperature is about 68 F, it's hard to see how a Mac's main CPU could be cooler than room temperature, given that it's a honkin' great source of heat.

    "When using Flash with Mail, Safari, iTunes, VLC, TextEdit and various background apps open, I peak at about 72ºC or 162ºF - I have a mid-2009 Macbook"

    Sure, and my mid 2009 MBP shows the same behaviour. The MBP and MB have pretty much the same thermal design, just different levels of bling on the casing! But a bit of Flash isn't a stress test, I bet your CPU is only at 60% or 70% load. If you wind it up to 100% I bet the temperature will soar. You can do this in lots of ways (Handbrake, Cinebench, Matlab, rendering, etc) but the simplest way is to open two Terminal windows and type yes > /dev/null into each.

    Try it, I bet you see the following
    - CPU temp rises, fan stays at 2000 rpm
    - CPU temp hits something near 105 C / 221 F, fans near 2000 rpm
    - fan speed rises over a few minutes, CPU temp gradually drops to about 95 C / 203 F

    Try it.

    Here are a few links to people with >100 C full load temps
    this one's really nice, graphs 'n' everything

    add both my Macs into that, a 2006 MB (Tj, max 95 C not 105 C) and 2009 MBP (Tj,max 105 C)
    etc etc

    As I said before, "....But re the OP's problem, his Mac is showing temperatures exactly the same as millions of other Macs. Telling him his temperatures are "very dangerous" is IMHO unhelpful and probably incorrect."

  24. johnnyham macrumors regular

    Jun 18, 2010
    Wow... talk about foot in mouth. I meant to type Celsius. Awkward...

    I ran the yes > /dev/null command as you suggested and got my CPU up to 97.69% capacity and left it running for ten minutes, but I never saw the temperature rise past 85ºC. I've also used Handbrake to rip DVDs before, but I've never seen it get past the 72ºC maximum that I posted earlier.

    On one of the threads you posted, Macbook pro and handbrake, I found this reply:
    So I think that explains why the OPs Macbook was having kernel panics because it was hitting the shutdown temp.

    I concede that you are correct, Pax. I was mislead by my own experiences and felt that 105ºC was far too hot, but as you've shown, it's possible, albeit not often. So I apologize for calling you out on the Celsius and Fahrenheit thing.
  25. Pax macrumors 6502a

    Dec 12, 2003
    Scary isn't it :). If you rip from a DVD the CPU can spend time waiting for the drive, so it never maxes out. I'm guessing therefore you have a pre-unibody Macbook, IIRC all of the CoreDuo and some of the early Core2Duo chips had a Tj,max of 95 C.

    Re F and C it's a pain in the butt isn't it. At least we're not designing space probes.

    Macs are designed to get very hot CPUs. I don't know whether it's "bad" for them or not, that's where the flaming starts. Personally I think Apple knows what it's doing, but I can't prove it.

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