Macbook fans run at different speeds at same temperature

Discussion in 'MacBook' started by zgotts, Jul 10, 2012.

  1. zgotts macrumors newbie

    Aug 3, 2011
    Macbook operating temperatures seem to have always been a major topic of discussion in the Apple community.

    One interesting thing I've noticed is on my two different Macbooks, the fans run at different speeds even at the same CPU temperature.

    My home computer is a white Macbook from 2006 with a Macbook 2,1 logic board inside (2.16GHz Intel Core 2 Duo) and a bunch of other upgrades. It runs incredibly smoothly, but the fan is loud as hell.

    My work computer is a 2010 Macbook Pro with 2.66Ghz Intel Core 2 Duo processor.

    Both run at around 60 degrees Celsius (according to smcFanControl) when browsing the internet and listening to music, and about 10 degrees hotter when doing web development work/running VirtualBox.

    For whatever reason, the White Macbook's fan runs between 4000 and 6000 (max speed) rpms at these temps, while the MB Pro is running at 2000 rpm at 60 degrees.

    Anyone know the reason for this? Are older Macbook fans designed to run faster/more sensitive to heat?

    I'd love to eliminate that fan noise on the White Macbook as that's really the only thing I don't like about the computer. I will likely be doing a ventiliation mod on the bottom case. I know it sounds crazy, but working this macbook has been a lot of fun, and it's not to hard to put everything on my back up bottom case if things go wrong.
  2. GGJstudios macrumors Westmere


    May 16, 2008
    The fans spin up as necessary to maintain temps in a safe range. They may not spin up at all, unless high temps are sustained for a period of time. The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C (221F), GPU Tjmax = 100C (212F) on i3, i5, i7 processors. (Source: Intel) If you're not already using it, iStat Pro will give you accurate readings of your temps and fan speeds, among other things.

    Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If you're constantly putting high demands on your system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just your Mac doing its job to maintain temps within the normal range.

    It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.

    Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level. If they're spinning up without increased heat, try resetting the SMC. (PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)

    The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks (except the new MBP with retina display, which has intake vents along the sides at the bottom). The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best.

    Learn about the fans in your Mac
    Apple Portables: Operating temperature

    For Flash-related issues:

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