Macbook late 2008 unibody getting heat slowdown

Discussion in 'MacBook' started by MindBrain, Feb 6, 2010.

  1. MindBrain macrumors regular

    Jun 8, 2007
    Hey I was wondering if I should be getting heat slowdown while gaming on my Macbook (9400m graphics, aluminum Oct. 2008) I first noticed the problem in X-Plane and was able to control it a number of ways (smcfancontrol setting fans to max, and using a cooling pad helped)

    So a while later I install bootcamp and windows XP, even with fans at max and the cooling pad, for some games I will get the slowdown after a few mins. I know it's heat related slowdown because if I quit when it happens I check the temperature of the cpu and it's around 200 degrees.

    I'm not sure how abnormal this is, I'm also still testing to see if using 2x antialiasing helps (by lowering framerate) but I'm not sure.

    I've read about reapplying thermal paste, but has this shown improvements in my particular model?

    I want to take it to the Apple store, but I'm out of the 1 year warranty, however, should they have something to do with it if the computer had the problem inside the warranty period but was not noticeable then, as I wasn't running high end games?

    If anyone has any help it would be appreciated. Btw my current temperature is 126 degrees, with just this firefox web window open. Thanks

    edit: I've found lowering the maximum prerendered frames option in the nvidia control panel, from 3 to 0 (will try settings of 1 and 2 later) helped. Anyone else doing hard gaming on their late 2008 macbook have any opinions, please, thanks. I've been running Dawn of War 2 demo as a sort of benchmark
  2. MindBrain thread starter macrumors regular

    Jun 8, 2007
    Wow no one has any advice? I'm just looking for people and run intensive games in Windows XP, and wondering what your temps are. Do you use a cooling pad, do you get heat slowdown when you don't use a cooling pad? What's the deal?
  3. Kat King123 macrumors regular

    Kat King123

    Jan 3, 2009
    Well this can be a problem or be normal it all depends on which model do you have the 2.0ghz or the 2.4ghz macbook.

    if its the 2.4ghz model then your fine but it is running pretty hot but the cpu can handle up to about 221F.

    But if its the 2.0ghz model then theres something wrong it can only handle about 194F.

    But for me i have a macbook similar to yours i overclock from 2ghz to 2.3 whenever im in windows 7 and i put the GPU up to it normal speed because apple likes to underclock:rolleyes: Never had any temp problems
  4. Pax macrumors 6502a

    Dec 12, 2003
    Istat nano?

    If you download Istat nano (a Dashboard widget) you can set it to show temperatures of the various components.

    What temperatures do you see when both CPUs are running flat out? Particularly for the CPU and the heatsink.

    If the CPU and the heatsink temperatures are within less than about 40 F of each other changing the thermal paste probably won't make much difference.

    eg if the CPU maxes out at 194 F then I would expect to see the heatsink at 158 F or hotter.
  5. MindBrain thread starter macrumors regular

    Jun 8, 2007
    Thanks for the replies. I have the 2.4ghz Intel Core2Duo.

    Upon running 2 instances of "yes > /dev/null" (2 since, 1 for each core I'm assuming, as running 1 puts my cpu use at 50%) After a few mins my cpu temperature is at 208 degrees, I don't know how much higher it can go because at this temperature I'm worried and I shut them down.

    Currently my cpu is 149 degrees, heatsink A 146 degress, heatsink B 126 degrees. About 80% cpu idle, listening to sound, 5 web pages open, no cooling pad. So according to Pax thermal paste won't help, however I havn't checked these differences at higher temperatures.

    What gets me is does other peoples macbooks control the heat (or generate less) more efficiently then mine (when we're running at same settings)

    Are there people out there running intensive games with no slowdown while not using a cooling pad? Or is it expected to use a cooling pad while gaming (in other words is it asking too much of the system to run intensive games with no cooling pad?)

    I guess if a cooling pad is pretty much required then the one I have just doesn't cut it. I'd like to have a nicer one like the Zefyr designed for macbook, but it's 75 bucks

    Well on the plus side I've found the option in the nvidia control panel "maximum prerendered frames" set to "0" helps a lot, but then again do other users have to invoke this option to keep their heat under control, I'm thinking my guess is no.

    Kat King do you run a cooling pad when you're gaming? And maybe that .1 ghz less makes all the difference, maybe I need to underclock my processor if that's possible. Seems like an ugly solution though.....

    edit: Was running X-Plane and watching my temperatures, the CPU hit a max of about 210 degrees, mostly the cpu hovered around 205 degrees, with heatsink A at 194 degrees, and heatsink B at 155 degrees. Pax what do you think about heatsink B, should it be closer to the cpu temperature like heatsink A is, or is it supposed to be a lot less? Thanks

    edit 2: I did another test with yes > /dev/null I tried it without my battery in the computer and once the fans maxed out the temperature didn't get above 176 degrees or so. So it runs a ton cooler without the battery. Is this normal, could I have a faulty battery that runs hot? Of course problem with running without a battery is if the cord gets unplugged and shuts me down.....

    edit 3: I learned running without the battery throttles down the that would explain why it runs cooler....

    edit 4: Well after doing more cpu load tests and seeing my temperature at 97 - 99 degrees Celsius it's my conclution this machine runs much hotter then it should, and hotter then other people similar computers...gonna have to take it to Apple to look at, would hope they can do something about it being out of warrenty, not my dang fault I didn't notice it when I first got it as I wasn't running demanding programs....
  6. Pax macrumors 6502a

    Dec 12, 2003
    OK, useful info. I don't think you have any problem. (I work in C not F so apologies if I do some conversions)

    (1) there is nothing wrong with your thermal paste.

    your heatsink temps are reasonably close to your CPU temps.

    I don't know the distinction between Heatsink A and Heatsink B. But

    CPU 205 F = 96 C
    Heatsink B 155 F = 68 C
    Difference = 28 C

    Those temperatures look high-to-normal normal. My MBP has about 25 C difference between the heatsink and the CPU core. Even if you replaced the paste I expect you would not make much difference to the number - it's simply very hard to suck heat out of the small area of the die through the silicon wafer and the paste.

    (2) the temperatures look perfectly normal for a 2.4 GHz device

    You have a P8600 which looks like it is specced to 105 C..... P8600 AW80577SH0563M (BX80577P8600).html
    (you could probably find the same info on the Intel website but it can take some searching)

    Most of the Core2Duos are specced to 105 C, the 2.0 GHz looked like an exception.

    Above 105 C the processor will start slowing down to save itself. Above about 125 C it will shut down

    (3) Apple seems to design its cooling system to run the CPU up to the spec limit, then cool it down to about 90 - 95C

    If you use the default fan control algorithm (NOT SMCfancontrol etc) I've seen the following on a couple of Macs.

    Run the CPUs up to 200%
    Temperatures climb to near or just over 105C, this takes a few minutes
    Fan speed doesn't start to rise until temperature is into the 90s
    Temperature continues to rise even though fans are increasing
    Fan then increases and after a few minutes pulls the temperature down to the low to mid 90s
    CPU temp sits at the low/mid 90s and the fans speed up and slow down to hold it there.

    This all makes sense - the computer knows most high CPU loads only last a short time so it doesn't ramp the fans up too quickly or it would be annoying. THe computer is happy to let the CPU reach 105 C, but not for it to stay there indefinitely. So it uses the fans to bring it down to the mid-90s.


    you are quite safe. The temperature seems quite high but the CPU is specced to cope with it. The fan behaviour seems funny at first but it makes sense to me. Your CPU will happily sit at 95 C for many, many years.

    On my 13 MBP (basically the same computer as yours) under 2x /dev/null if I leave it for 10 minutes the CPU settles in the low/mid 90s C with heatsink B at just under 70 C and the fan at about 3000 rpm. The fan speed changes up and down to keep the CPU at that temperature.

    So our computers are both doing the same thing - it's nominal.

    Your computer should NOT be slowing down at these temperatures. You used to be able to use CoreDuoTemp to look for the CPU throttling its clock speed, but I'm not sure this is compatible with Core2Duo.....
  7. MindBrain thread starter macrumors regular

    Jun 8, 2007
    Well I just got out of Quake Live game (in Windows XP), I would check the temperature every minute or 2, after about 5 mins or so I got the slowdown, I checked real quick and was at about 94 degrees Celsius, so it looks like to me the CPU throttled down at about 95 degrees Celsius. This is without the cooling pad, vents are not blocked

    I will try this test now in X-Plane in OSX

    Edit: Well I tried in X-Plane plane, the slowdown seemed to come when the temp hit about 102 degrees

    Pax do you know of a definitive way to test all of this, like if I took it to Apple how would they test it? Is there a stress test program that works the cpu and gpu and notes the clock speed and at what temperatures the clock speed changes (throttles) etc. Thanks

    Edit 2: Ok here's what I'm seeing. When I'm running in WindowsXP the cpu will throttle down at about exactly 95 degrees celcius. In OSX it throttles down around 102 (maybe 105, and the 102 is what I'm seeing after it's cooled down for a second)

    Running the 2 "yes > /dev/null" processes my temperatures hover around 98 - 100 degrees celcius, with the fans already going at MAX (won't get any cooler)

    I'm getting the impression that most people's computers running at full load are seeing temps more around 80 - 85, seems like my computer gets way too hot
  8. Pax macrumors 6502a

    Dec 12, 2003
    How do you know you are getting slowdown? How do you know it is the CPU throttling down? Do you have something that measures the CPU clock speed?

    When you play X-plane for an extended period, what temperature does the CPU settle down at? What temperature is the heatsink at?

    What happens if you use the standard fan cooling, OSX and no SMCFanControl. ie if you use the MB as Apple intended it?

    98-100 C is warm but is within specification. As I said mine runs at about 92 C, I have seen others running at similar values.

    Putting it bluntly, how do you know that you have a problem? 98-100C is not the symptom of a problem, it shows the CPU and Macbook cooling system working nominally.
  9. MindBrain thread starter macrumors regular

    Jun 8, 2007
    The temperature never really settles down, it steadily climbs to about 102 degrees celcius, then the system heat safety thing kicks in, the game turns to a slide show (really strange slowdown, the framerate fluctuates from very low to normal every 2 - 4 seconds) After the slow down starts eventually the temp will lower to like 76 degrees and I'm still stuck with a slideshow game...

    I've tried that and believe I noticed no benefit. Not long after I first noticed the problem I even formatted my system (computer was cluttered anyway) to see if it would help but it didn't. I'll uninstall smcfancontrol and try the yes command again to be sure

    I'm getting the impression from what I can scour on the web that running at 100 degrees celcius for any real period of time is insane. Even if I can cool the thing just enough to not trigger the safety slowdown mechanism, how long before I have a nice unibody aluminum's crazy right on the edge of its capacity

    I can tell the slowdowns are a result of the heat because I can see in just about any intensive game, a distinct drop in frame rate (at the temperatures I mentioned above) it's really obvious and makes the game unplayable, only way to fix it is to quit the program and let the computer cool.

    By the way this is after only maybe 5 or 10 mins with the fans already going at MAX.

    It's silly because I've had to come up with a tweak every time the problem creeps up, in X-plane I got the cheap cooling pad and smcfancontrol, ok that helped some, installed bootcamp, had to mess around with nvidia options, games where you can set a maximum fps (I put 40) seems to help, I guess less strain on the grahpics card, which leads be to believe the gpu is getting too hot as well...

    I'm just trying to find other people that might have noticed this situation, should I be expected to need a high end cooling pad? A bunch of other questions. Anyway I'm taking it into an Apple store on Friday 11:00am, I'd like to run some of the cpu tests on any 2.4ghz machines they have there and see how hot they run.......I'll just have to see what they say I guess....
  10. Pax macrumors 6502a

    Dec 12, 2003
    Maybe you do have a problem, it sounds odd

    "After the slow down starts eventually the temp will lower to like 76 degrees and I'm still stuck with a slideshow game..."

    your CPU should not be throttling below 105 C. No way should it be throttling at 76 C. The fact that you still see slowdown at 76 C would seem to me to indicate another, non-CPU-related problem.

    Have you tried resetting the SMC? You can find instructions on the Apple website. The SMC controls low level hardware functions like fans and sensors.
    check out the Intel specification document, PROCHOT is not invoked below 105C for the Core2Duos.
    If your CPU was throttling it should throttle its clockspeed down until the temperature drops below 105C, then go back to full speed. You would see the CPU temperature hold at around 105 C.

    Maybe you have another problem... something to do with the graphics getting too hot... I don't know.

    The heat pipeline goes

    CPU > thermal paste > heatsink > heat pipe > fan blown air > outside air

    Your heatsink temps seem to indicate that the thermal paste is OK. Your fan presumably works OK. I guess it's possible you have a bad heat pipe or air duct, something like that.

    It doesn't sound like anything obvious, hopefully Apple can sort it out.
  11. bearcatrp macrumors 68000

    Sep 24, 2008
    Boon Docks USA
    The heat will cause slowdowns after a certain temp on ram modules. I have the 2ghz model and have to run my fans to keep my temps down or i get stuttering even surfing the net. I use smcfancontrol and set it at 3000 rpm's to keep it cool. What brand of ram modules are you using?
  12. Pax macrumors 6502a

    Dec 12, 2003
    Interesting idea. It looks like good DDR2 RAM should be specified to operate at 85 C or similar. If the OP's CPU is at 76 C then the RAM should be much cooler... it's placed quite a long distance from the CPU and heat pipes.

    Even if the CPU die was at 100 C I can't imagine the RAM being particularly hot.

    Here's just a random DDR2 sample (I'm aware it's not the right stuff for Macs, it's just an example)

    So I can believe that the RAM could cause stuttering, but not at the OP's CPU temp of 76 C????

    I wonder if it could be the graphics - the graphics chip has a TDP of 12 W or similar, quite a big dissipation, it could get pretty hot in there...
  13. MindBrain thread starter macrumors regular

    Jun 8, 2007
    I have 2gb of the default apple ram. The 76 degrees celsius is sort of a ballpark figure. It seems the more tests I do the more varied results I get. I only mentioned it because at one time it was the temp i saw after I noticed the system slowing itself down, which if I'm correct confirms that it is indeed heat and a safety feature kicking in. I loaded up X-Plane the other night and got the same issue, after the system slowed down though I saw temps of 90 degrees celsius, so I don't know whats going on, it was a slideshow though.

    Still havn't gone to Apple yet, gonna try to make it on Tuesday, basically what I want to know is should my cpu be at 100 degrees celsius with 100% cpu load and fans going at max. This just seems a tad (understament) hot. What's worse is I don't think the "yes > /dev/null" test even stresses the graphic card, so that heat is not even being factored in.

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