Heat/power in iMac vs. MacBook Pro

Discussion in 'MacBook Pro' started by Michael CM1, Dec 22, 2009.

  1. Michael CM1 macrumors 603

    Feb 4, 2008
    Maybe someone can help me understand this a bit better. I have a MBP with a 2.16GHz CPU. I think it's about 2.5 years old. It has the ATI x1600 GPU. My dad previously had an iMac G5 2GHz but now has one of the new iMacs at 3.06GHz.

    When running iStat, I can notice an obvious difference in the CPU temperature. I don't think my MBP runs less than 120 degrees idle, while the iMacs were easily under 100. I haven't seen the new iMac while doing CPU-intensive tasks, but the old iMac never got above 140 if I'm not mistaken.

    As I'm encoding video on the MBP for a DVD using iDVD, it's getting up to 187 degrees. The CPU is using about 125 percent of my processing power -- 200 percent max if you didn't know. The temperature is the same even when HandBrake gets up to about 190 percent of processing.

    I basically want to know if this is normal. I've been having trouble getting video from iMovie onto a disc, sometimes because the computer completely freezes. I've probably wasted six to 10 DVDs in the process. I can easily convert these things to MP4 video files, but physical discs are a pain. I almost wonder if my next computer should be an iMac and then use my notebook on the go as almost a netbook-style computer since it will be "slow" in a couple of years.

    I thought iMacs used a lot of notebook components, so I'm confused on why my MBP runs so darn hot. I do use clamshell mode almost all the time with an external monitor, but fully opening the MBP display doesn't do much. good. I also have a USB-powered fan under the MBP that tilts up to give some fresh air under everything. The bottom enclosure is 90 degrees, but I know that heat can rob a computer of power.

    Thanks for any input!
  2. DoNoHarm macrumors 65816


    Oct 8, 2008
    the imac is a newer computer with more powerful components running at a lower capacity. it doesen't have to work as hard, even at idle. that's probably why it is operating at a lower temperature. also the fans may be more efficient since they don't have to worry about squeezing everything into such a small space under the keyboard.
  3. Mangoes macrumors newbie

    Jan 3, 2010
    Macbook pro heat issue

    My Macbook Pro also heats up fast whenever I watch video or use video chat.
    It goes up to 90 degree centigrade. I am not sure whether this is normal behavior or not.
  4. MacsOnAnabolics macrumors regular


    Jul 31, 2009
    Rancho Cucamonga, CA
    I would say that it is normal for the MBP to heat up considerably, however, the temps you have described above seem too hot. Are you sure your fans are working properly? Download smc fancontrol and test the rpm of each fan separately to rule out fan hardware failure since this is a common problem with older machines.
  5. applebook macrumors 6502a


    Jul 21, 2009
    This is not remotely normal. Even under 100% load for hours, a modern MB should not be hitting 90C. You need to download smcFanControl and manually turn up your fans when you running HD video or heavy flash.
  6. applebook macrumors 6502a


    Jul 21, 2009
    Michael, the iMac has so much more space for better cooling, so of course it will run less hot.

    You need to install smcFanControl because your MBP is clearly not turning up the fans quickly enough to match your CPU loads.

    I find that Apple has chosen quietness over coolness because if left to its own devices, the fans of MBPs will rarely ever go above their lowest (2000rpm) unless your are using lots of CPU resources for a long time.

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