iMac overheating in Bootcamp?

Discussion in 'Windows, Linux & Others on the Mac' started by sng08, Oct 23, 2010.

  1. sng08 macrumors member

    Aug 30, 2010
    Hello all,

    I currently use an iMac i7 with Windows XP SP3 installed on the Bootcamp partition. I've noticed recently that when I'm on the Windows side for a long period of time the iMac gets quite hot and the fans are raging with a loud roar! Obviously, this does not happen on the Mac OS side. I got quite concerned, so I restarted it in Mac OS to check the iStat. The CPU fan was over 2000rpm and some of the temps just reached over 60 degrees C. So I decided to keep it in Mac for the time being and everything decided to calm down to the 'normal' temperatures.

    I've searched Mroogle / Google for solutions and it appears people are using smc Fan Control for Windows to increase the fan speeds. I'm not sure if this is the right path to go down where I can override the fan speeds and just put up with the fan noise... but is there another solution? Are there any drivers released to help deal with this issue or is it a windows problem?

    Many thanks in advance.
  2. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    What were you doing in Windows? If you were gaming or doing something else intensive, then it's not a surprise that your temps are higher
  3. sng08 thread starter macrumors member

    Aug 30, 2010
    Hi Hellhammer,

    No gaming involved on the iMac. I was just web browsing, and the ocassional office/acrobat documents.

    I fear that later when my work becomes more intense which will require the use of CAD/3D programs that the temps will increase drastically!
  4. aki macrumors 6502a

    Mar 2, 2004
    There are lots of very informative threads on this topic. Here is my considered view for what it's worth.

    Firstly, iMacs do run on the hot side. They are pretty cramped (yes even the 27") and designed to be svelte. That has a cost.

    Second, they get hot to the touch. This is most certainly by design. Touching your iMac tells you nothing except that the heat dissipation is working well. If you want to know what's going on inside, which is the point, use iStat or similar.

    Third, for normal use, the iMac does not require user intervention. This begs the question "What is normal use"? Here's my take. If you upgrade your hardware regularly, don't worry about temps. If you want or may want your iMac to last into the 3 to 5 year range, you should give it a thought. If you use your iMac mostly for email and websurfing and writing papers, forget about temps. If you do marathon gaming sessions, if you often game in bootcamp Windows, or if you do video processing or other "heavy lifting", you should give temps some thought.

    Fourth, most people who worry about temperatures worry about them needlessly; see point three above.

    Fifth, if you do use your iMac for heavy work or often use Windows and do want your machine to last a bit longer or at least know what's going on, the current prefered solution (imo) is iStat or Temperature Monitor or similar, which will give you temps in the menubar or in the Dashboard (OSX side only), and smcfancontrol, which will let you manually set minimum fan speeds (the setting can only be done from OSX, although you can have the fan speed settings carry over to a bootcamp Windows session provided you do a restart and don't switch off the iMac).

    Sixth, if you are setting fan speeds and looking at temps, what should you be looking for? The GPU and CPU are precious and expensive to replace obviously but they are also rated for quite high temperatures. The iMac is designed to shut itself down before you get to that point. What is rather more fragile is your internal HD. High temperatures don't kill HDs immediately, but they do reduce lifespan/increase failure rates. Of course you should be timemachining or similar anyway; but replacing a HD is tedious and stressful and can be very inconvenient. Again, having given due consideration to the points above, I think it's good to set speeds to keep your HD temps in the low 50s C. Under 50C is fine, over 55C is bad, in between is, well, reasonable given what the iMac is. (I should note when I talk about temperatures here I'm talking about high temperatures suistained over a period of time. Spikes in temperature, when you are transcoding a youtube clip or something, that's not worth being concerned about. I'm thinking here about all-night Crysis sessions or whatever.)

    Seventh, and final point. Environmental conditions play a role (more than I originally thought). Depending on where you live, ambient temperatures will have an effect - I'm in Japan and temps are clearly higher in summer than winter inside the iMac. Also, if you live in a dusty environment, it's not a waste of time to dust around your machine and desk regularly - your fans will suck up that dust over time.

    Eighth and actually final point. External fan solutions sound better than they may actually be. I'm not an engineer of any description, but I have read authoritative-sounding accounts of how the fans in the iMac are carefully and cunningly placed so as to maximize efficiency, by directing airflows from certain areas to other certain areas over so and so components. Which is to say, it's all a pretty neatly designed system. There used to be mods around where people would carve holes in the backs of their G5s (this is in the plastic era), and electrical-tape fans on there or what have you. Bad idea (generally speaking) - it just messes with the airflows that some team of very clever Apple engineers burnt countless nights laboring over. Or something. I'm being verbose, the point is, placing little desk fans at the base of your machine or pointing your fan at the air vent in the back might look like its helping - hey, it's cool air, right? - but it may or may not actually be that simple.

    BTW If you do elect to use smcfancontrol, it's generally better to trying uping all three fans a small amount than one fan a lot. Again, they are designed to work in concert.

    Update: iStat Menus versions 3 and above (no longer, alas, a free product) allow you to manage fans similarly to smcfancontrol, along with monitoring a billion other things. Its settings carry over to bootcamp sessions like smcfancontrol does. However, iStat Menus displayed some odd behavior on my machine, so I reverted to smcfc.
  5. chris650 macrumors regular

    Jun 15, 2010
    i am new imac user, i5, 27"

    the top is pretty warm... i never heard any fan

    how do you check for temp and fan speed? is it in the mac osx system?
  6. aki macrumors 6502a

    Mar 2, 2004
    Install Temperature Monitor or iStat. Both are free or have free versions.
  7. chris650 macrumors regular

    Jun 15, 2010
    my HD is 55

    can someone list some healthy temp range?
  8. MythicFrost macrumors 68040


    Mar 11, 2009
    In OS X my HD temp was 60, CPU ~45, GPU ~66, ODD ~57, etc., and that was just regular use, no gaming, etc., same temps under Windows more or less. Gaming, my GPU has been up to 87c and is still fine, although my fans aren't blaring, in fact if it wasn't for smcFanControl they wouldn't even go above ~2k RPM.

    I've got on 09 i7 iMac.


    I've got my HD fan set to spin @ 3.2k RPM, CPU @ 1.6k and optical drive (ODD) @ 1.8k, the sound is only faint with and with background noise (or music, game, etc.) I can't really hear it at all. It brings my temps to: 47 for the HD, 39 for the CPU, 55 for the GPU, 46c for the optical drive.
  9. aki macrumors 6502a

    Mar 2, 2004
    I've read that HD lifespan starts to deteriorate once you get to 50C and rapidly above 55C. What you consider a reasonable temp depends on how long you need/want your HD to last, what your backup routine is like, how paranoid you are as a person etc etc. For myself, I try to keep temps as close to 50C as possible.

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