Cooling Mat/Pad Doesn't Work on MacBooks?

Discussion in 'MacBook Pro' started by boba7523, Oct 11, 2012.

  1. boba7523 macrumors regular

    Joined:
    May 14, 2011
    #1
    Hey guys, i just bought one of these cooling mats, which I believe is the exact same item as the ThermaPak one. Anyways, did it work for anyone? I was using Skype video chat+ browsing facebook pictures, and my 2011 13" MBA shot up to 180-190 degrees with fans kicking in at 6000 rpm.

    I didn't feel the crystals in the cooling mat becoming solid, heck the cooling mat was barely hot! It wasn't sitting level, but even if i tried forcing my MBA to sit flat on the mat, temperature wouldn't decrease..... Is it because only the top part of the MacBooks get hot and not the ENTIRE laptop?.... Anyways, just wondering if it worked for anyone because i'm thinking about returning this otherwise convenient technology....
     
  2. Queen6 macrumors 603

    Queen6

    Joined:
    Dec 11, 2008
    Location:
    Enjoying Better Things
    #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. switon macrumors 6502a

    Joined:
    Sep 10, 2012
    #3
    RE: Passive cooling mats...

    Hi boba7523,

    Just a comment about chemistry and the operation of these passive cooling mats ...

    I believe these operate by the melting of a crystalline material. When a crystal melts, its temperature stays the same until all of the crystals are melted, then the temperature can rise above the melting point temperature of the crystals. Because the Enthalpy of Fusion is typically quite large, and almost always much larger than the Heat Capacity of the melted liquid, this means that the temperature of the mat will stay the same as it continues to absorb heat from the laptop. Only when all of the crystals have melted, will the temperature of the pad begin to rise, and at this point the mat has essentially exhausted its ability to cool your laptop. You then have to wait until the mat releases all of the heat, from the Enthalpy of Fusion, from the liquid to recrystallize into solid form again.

    This is the same reason that a glass of ice water stays at 0C (=32F) until all of the ice has melted, only then will the temperature of the water rise above 0C.

    In conclusion, the cooling mat will stay at the same temperature as it cools the laptop (the melting point of the crystals in the mat), and once the temperature of the mat starts to rise, the mat is no longer capable of cooling the laptop. You then have to remove the mat and allow it to cool until the liquid has solidified into crystals once again before it can be used to cool your laptop. I doubt you can "feel" the crystals since they are embedded in some sort of gel matrix that keeps them separated and flexible, so I wouldn't worry about not feeling the crystals. And it is the melting of the crystals that cools the laptop, not the other way around.

    Regards,
    Switon
     
  4. boba7523 thread starter macrumors regular

    Joined:
    May 14, 2011
    #4
    I guess i wasn't specific enough in my first post.

    This cooling mat did not "cool" my MBA AT ALL. During the entire skype video chat + facebook, my MBA was at 180-190F.
     
  5. switon macrumors 6502a

    Joined:
    Sep 10, 2012
    #5
    RE: Cooling of laptops...

    Hi boba7523,

    You're being specific, allow me to be specific.

    My first response was simply to correct a misconception of how the chemistry of these passive laptop coolers work. That said, whether or not it cools your laptop depends upon whether or not the "crystals" melt. If the mat has contact with the bottom of your laptop, then the mat's surface is heated by the laptop and the "crystals" within the mat will melt and therefore, yes, the mat does cool your laptop, that is, the mat extracts heat from your laptop. (But the mat extracting heat does NOT mean that the CPU temperatures will be any lower --- see below.)

    Now for the kicker: Does this cooling by the mat lead to a lower temperature of the CPU? Probably not!!! Why not? Well, because the laptop is cooled so much more efficiently by its own internal exhaust fans. Probably something greater than 95% of the actual heat exiting your laptop is removed by the exhaust air from the fans. And since the fan speed is controlled by an algorithm based upon the temperature sensors within your laptop, if the temperature of the CPU drops below some value the fans are slowed so that the temperature doesn't keep dropping. In other words, the temperature control system is designed to keep the CPU temperatures at or below a certain value, and so if the mat's cooling (which I suspect is not much) dropped the CPU temperature below some value then the laptop slows its own fans so the CPU temperature doesn't keep dropping. Hence you will not ever see the cooling effects of the mat cooler show up in a temperature drop of the CPUs. It just isn't possible since 95+% of the heat is removed by the fans, and the fan speed is controlled by an algorithm based upon the CPU temperature.

    So, is it a good thing to have the fans slow when the CPU temperature starts to drop below some predetermined values? --- sure it is, for slower fans mean less fan noise and a quieter computer. Also, fans are driven by mechanical motors that suffer greater frictional wear and tear when they run at higher speeds, so dropping the fan speed leads to a longer life for the fans. Some suggest running their fans at full speed (6000rpm) all the time, but I suspect that this would cause the fans to fail way before the few degrees lower temperatures of the CPUs at low loads, say 50 to 60C, gains extra life for the CPUs. In other words, running a fan at 6000rpm to lower a CPU temperature from say 70C to say 60C might extend the life of the CPU a small percentage, but decreases the life of the fan by a high percentage. Of course, when the CPU temperature gets high where its lifespan would indeed be shortened, then the fan speeds are ramped up to full speed; and if the CPU temperature goes even higher, then the CPU frequencies are throttled until their temperatures lower to a reasonable value.

    In a nutshell, unless the cooler can actually cool more efficiently than the fan exhaust, the cooler will not lower the CPU temperature nor produce much of an effect. The laptop's fan/heat pipes system is so well designed that no additional cooling is required. How can one improve the fan exhaust cooling? By lowering the temperature of the intake air! So, if you really want to cool your laptop, you would turn on the air conditioner. Even this won't actually lower the "normal, low load" operating CPU temperature, since the laptop will simply lower the fan speed even more in the air conditioned room --- you won't see lower CPU temperatures, but you will see lower fan speeds.

    Caveat: Now perhaps there are coolers that somehow force more air into the laptop's intakes and thus can force more exhaust air from the laptop than what is already available by the laptop's own fans, but I doubt it --- the fans are pretty efficient at doing this already. You might think about jury-rigging some air pipe system to force air into the laptop's intakes, but without a decent seal I think this would be tough to accomplish.

    In conclusion, because the laptop's cooling system, based upon internal exhaust fans and heat pipes, is so efficient at removing heat from the laptop (I suspect something over 95% of the heat is removed by the exhaust fans), then any external laptop cooler is going to have a minimal effect at best, and because of the fan speed control system based upon CPU temperature, an external cooler won't actually lower the CPU temperature any until the fan exhaust mechanism is maxed out, that is, only at 100% CPU loads will an external cooler ever lower the CPU temperature, and then by only a small amount.

    What do you think?

    Regards,
    Switon

    P.S. I wouldn't expect the passive cooler to produce any reduction in CPU temperature, unless your Skype actually produces 100% CPU loads, and, if it does, then the cooling would be minuscule (<1C probably).
     
  6. wordoflife macrumors 604

    wordoflife

    Joined:
    Jul 6, 2009
    #6
    Cooling mats and pads and fans don't really work well with Apple computers because the exhaust is actually located on the hinge.
     
  7. boba7523 thread starter macrumors regular

    Joined:
    May 14, 2011
    #7
    Thanks for the informative post switon, i learned about from it :)

    That said, there HAS to be a cooling pad that actually reduces the temperature of the MBA... I cannot handle 180-190F on my lap, and i cringe whenever the temperature goes above 170F and the fans kick in... I like it if my CPU temperature can stay in the 100F-160F zone where the fan's rpm is ~2000 rpm....
     
  8. switon macrumors 6502a

    Joined:
    Sep 10, 2012
    #8
    RE: UltraFan...

    Hi,

    If you want your CPUs to be cooler, then the best way is to run your laptop's fans at higher speeds, and I believe there are a number of apps that give you that ability. One I recall is UltraFan, for instance. This app allows you to set a temperature range and it will increase the fan speeds until your specified range is met.

    I believe that it will be difficult to find a commercial laptop cooler that actually lowers the CPU temperatures, for the reasons I gave earlier, especially those with regards to Apple's algorithm for controlling fan speeds and the fact that the fan exhaust removes the majority of heat from the laptop. But if you replace Apple's control algorithm with one of the third party apps, then you can increase the fan speeds to lower the CPU temperatures, of course at the expense of more fan noise and potentially shorter lifespans for the laptop's fans.

    Switon
     

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