47 Degrees Celsius diff between heatsink and CPU?

Discussion in 'MacBook Pro' started by TheRdungeon, Oct 13, 2012.

  1. TheRdungeon macrumors 6502

    Joined:
    Jul 21, 2011
    #1
    Hi all, I'm sick of the fans spinning up anytime I do pretty much anything in Logic and staying on. I also noticed that there's always a difference of around 20deg when idling, so ran dev > null in 8 windows (early '11 2.2 15") and left it for ten mins then took this screenshot:
    [​IMG]

    So that's a 47deg difference under load, the heatsink has sat between 46-49 deg the entire time whilst doing this.

    I understand that it's not overheating, but this seems like a textbook case of bad thermal paste if I'm correct? As this is a huge discrepancy and I'd do anything to get this thing cooling down quicker. It's propped up on a desk so is getting enough air beneath it
     
  2. Queen6 macrumors 603

    Queen6

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    #2
    If you are concerned about temperature and want to reduce it elevation of the rear of the machine helps, as sitting flat on the desk only reflects the heat back to the base of the Mac. You can buy passive aluminium coolers like Rain Designs Mstand or iLap. Most powered coolers are designed for PC notebooks and don't work overly well with Mac`s if at all. One cooler that does work efficiently is the Moshi Zefyr 2, as it`s principle of cooling is specifically designed for Apple portables, by blowing the air horizontally across the base of the computer, however don't expect miracles.
    [​IMG][​IMG]
    [​IMG]

    Link: Moshi Zefyr 2
    A cheap USB fan can achieve the same if strategically placed, not as elegant mind, nor as easy to put in your notebooks case :p but they do help to reduce case temperatures.

    You can use software to override Apple`s own cooling algorithm by manually taking control of fan RPM and setting up power profile presets with SMC Fan Control 2.4, or here with UltraFan which allows you stipulate a preset temperature and the software will automatically raise and lower fan RPM`s to keep the system at the predefined temp, which i personally feel is a far more elegant solution. At the end of the day you want to control your system temperature, not your fan rpm`s. For me SMC is now pretty much redundant with the latest release of UltraFan having manual control of the fans RPM, and subsequently i am starting to uninstall it from my own Mac`s. SMC FC is a great app, however although it`s recently updated, functionality is limited compared to some newer apps, equally SMC Fan Control is rock steady stable and a finished product.

    Strictly speaking Apple`s own cooling algorithm works, albeit at sacrifice of increased temps for quieter operation. This has always been the Apple way and is really nothing detrimental to the system, i have one MBP from 2008 all original barring a recent fan change that has an uptime of over 30K hours. The latest MBP`s need less assistance in remaining cool; for some it`s simply disconcerting the heat generated and transferred to the case, although it`s perfectly normal as the aluminium acts as a heat-sync. i have to deal with elevated ambient temperature so at times a software solution is useful. Apart from the passive cooling the Mstands bring they also offer a very sound ergonomic solution. A passive cooler and UltraFan will maximise the cooling, there is little else you can do short of reducing the ambient temperature or the system load. If I know i am going to push a system i will close all apps that are not essential as this can and does make an impact to system temperature.

    High temperatures in general is not overly harmful to your systems, what is far more detrimental is thermal stress, where temperatures rapidly fluctuate by significant margins over a short period of time. Anyone striving for great longevity should look to minimise rapid temperature changes, here UltraFan is your best friend.

    Using a RainDesign Mstand, a Moshi Zefyr 2 and latest version of UltraFan I can reduce temperature by over 20C when transcoding an MKV video file, and that is something worth thinking about;

    • Apple default cooling algorithm 99C - 103C (still on Mstand) fans 4K and escalating :eek:
    • Mstand, Zefyr & UltraFan 79C - 82C fans at 5.8K :cool:

    The old adage still applies; it`s easier to keep a system cool, than cool-down an already hot machine. This being said it`s not strictly necessary, equally it`s nice to know that there are options for reducing temperature out there.
     
  3. Queen6 macrumors 603

    Queen6

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    #3
    I have a Late 2011 2.4 i7 15" MBP at home, when i get back i will check the temperatures, i certainly don't remember such a large difference, 10C - 20C maybe...
     
  4. TheRdungeon thread starter macrumors 6502

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    #4
    Cheers that would be good

    ----------


    Cheers this looks like a copy/paste reply though? As mentioned I keep it elevated and there's no point using SMC as it's fan noise I'm trying to cut down on
     
  5. Queen6, Oct 14, 2012
    Last edited: Oct 14, 2012

    Queen6 macrumors 603

    Queen6

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    #5
    I will update once i run a couple of tests, i just want the 2011 to finish up some work first.

    Yes it is very much a "canned" response as there are so many posts on this theme every week. For most it`s a question of getting used to a new Mac, some are simply not comfortable with the high external temperature etc. In your case there may be more going on, my 2011 is running a difference of 16C under a light load, which is not vastly different than your systems idle, all the same 40+ is a lot.

    I would still be inclined to give UltraFan and or SMC Fan Control a go; I find that be increasing the air flow to 3K can help with keeping the overall temperature down. My issue is once i plug in the external display (HDMI over Thunderbolt) the temperature really escalates as does intrusion by the fans. The max temp under load will peak at mid 90`s centigrade, than the fans will reduce CPU temp to upper 80`s C. Using UltraFan i can generally keep the temp sub 70C and the fans are not overly intrusive, without UltraFan the temperature just rises to the point where Apple`s algorithm kicks up the fan RPM, same issue with a hotter computer :rolleyes:

    Just shutdown UltraFan and CPU temp has risen from 65C with fans around 3K to 80C with fans at 3.7K with the external display unplugged. i do hear you as i like to work at night when it`s quiet and equally i don't care for Apple`s "turbojet" sound effects, when the system is loaded and the fans really spool up.

    FWIW The Retina is far better behaved and in general runs much cooler and of course quieter. I don't perceive that my 2011 MBP is a bad or running particularly hot if anything it seems to run a little cooler than what some have posted across the web...
     
  6. Queen6, Oct 14, 2012
    Last edited: Oct 14, 2012

    Queen6 macrumors 603

    Queen6

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    #6
    Well were back and the good news, at max CPU my system reports 40C difference between the CPU diode and CPU diode with Istat, so it looks like you have no issue, or we both have a problem :p Seriously looking at the sensors with Bresink`s Temperature Monitor CPU diode is hitting 90C and CPU Proximity 69C, which makes a lot more sense, it also reports Heatsink 1 & 2, "Heatsink 2" coincides with Istat`s CPU Heatsink.

    Safe to say it`s just a matter of software, i normally use Bresink Temperature Monitor to help with temperature related issues or just trying to figure out a more elaborate way to stop the "Turbojet" kicking in ;) Temperature Monitor can produce graphs so it helps to see whats happening over time and set the best default value for Ultrafan, too low will result in greater fan activity, too high and it`s back to the "toaster"

    As for you question, you may gain a little by replacing the thermal paste, although i tend to think all that will happen is that the system will just get to the same temperature sooner or later, no miracles here. What i have observed over the years with Mac`s is that you can make incremental steps, by using a passive stand, the right type of powered cooler, and a software solution adds up to a sizeable reduction in temperature, lower the temperature less intrusive the fans. Unfortunately once that Quad Core starts firing on all cylinders there is little that can be done to stop the fans from spooling up :(

    One last thing i only run what i need to run, as everything adds up thermally the less the CPU & GPU have to deal with the better here Activity Monitor is your friend :p
     
  7. TheRdungeon thread starter macrumors 6502

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    Jul 21, 2011
    #7
    Hey thanks for testing yours, yeah damn I know the sandy bridge is a hot puppy, love the power of the quad core but sometimes wish I could hold it back to get less heat. Not really a huge issue but I find when the discrete GPU is on it's pretty much constantly running the fan. Annoying droning thing.


    I find using a lighter as a stand is actually pretty good :p keeps it at a nice slight angle and doesn't block the fans or anything in the process
     
  8. Queen6 macrumors 603

    Queen6

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    #8
    One more software solution is gfxCardStatus, it allows you to take control of the GPU switching, also just handy to see the dependencies and what is exactly triggering the discrete GPU
     
  9. TheRdungeon thread starter macrumors 6502

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    #9
    Yep already use that, just a pain you can't physically run an external display on the HD3000
     
  10. w00t951 macrumors 68000

    w00t951

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    Pittsburgh, PA
    #10
    I don't think that's normal. Assuming the sensors aren't malfunctioning, it indicates a giant inefficiency in heat transfer between the CPU die and the heatsink. I have the same generation of Mac as you, but with a faster processor - I can tell you that those numbers aren't normal.

    I'm guessing that the CPU is getting extremely hot and automatically throttling itself to remain under Intel's max specs of 100C.

    In case you wanted to tackle a thermal paste change yourself (it's not difficult - just MAKE SURE YOU HAVE THE CORRECT DRIVERS!), here's the URL for an iFixit guide.
     
  11. yashrg macrumors regular

    yashrg

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    Feb 21, 2008
    #11
    Mine is a late 2006 model MacBook Pro that I have recently re-applied the thermal paste on. And iStat is showing CPU at 38C and CPU proximity at 34C. I haven't been doing things that max out the CPU though; and that is why I wanted to ask what kind of stress test do you suggest I run?
     
  12. seveej macrumors 6502a

    seveej

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    Helsinki, Finland
    #12
    One more vote for bad thermal paste.
    I'm here with an early 2011 quad core, and my difference between CPU and heatsink are 10% (4 deg difference in the forties (semi-idle), 10 degrees difference after 30 mins of handbrake).

    Keep in mind though, that the discrete GPU, while heightening the aggregate thermal load (and power consumption) does in fact have the advantage that it spreads the thermal load somewhat (two chips, two heatsinks - albeit on the same heatpipe), compared to the integrated which is located on the CPU chip.

    RGDS,
     
  13. TheRdungeon thread starter macrumors 6502

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    Jul 21, 2011
    #13
    Cheers, looks like I may have to go down the thermal paste route, even slight CPU activity on an external display is driving the fans up. Agreed about the heatsink thing, but it's clearly much hotter overall than the HD3000
     
  14. Mrbobb macrumors 601

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    Aug 27, 2012
  15. dusk007 macrumors 68040

    dusk007

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    Dec 5, 2009
    #15
    Heatsink heats up slowly. So take care how you interpret the results.

    I have a 2010
    65C the CPU
    54C the heatsink
    2.4k fans

    now after putting some more load on it. Flash dailyshow, + a 9Mbit video in vlc in the background just to make some noise. That is not max load but quite a bit for my old notebook.

    fans 6k
    77C CPU
    51-52C heatsink

    So the heatsink actually went down in temp.

    Initially they didn't heat up at all while the CPU temps jump almost instantaneous. Later they actually go down due to less passive cooling (relatively) and more active fans.

    The notebook has been on for hours so this might be the cause for my heat sink being generally hotter than yours.
     

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