iMac 21" Temperature Change

Discussion in 'iMac' started by Alejopeth, May 15, 2015.

  1. Alejopeth macrumors newbie


    Feb 10, 2015
    Hi, i have a 2009 iMac that usually works at 44ºC-50ºC, i use SmcFanControl years ago to lower the temperature, before installing SmcFanControl my iMac could reach 60ºC-70º, so i think that app is so helpfull, even when the fan sound increases a lot.

    Since i installed SmcFancontrol i always noticed that my iMac reach a point when i work a lot and the temperature goes down even more than 44ºC, at that point is rare to see a temperature hotter than 38ºC even using the same apps that make the computer reach 50ºC (Photoshop - 3D renders - Video Games - Music Production stuff), i don't know why that happens, i think is a "defensive" state of the computer, but is kind of helpfull because when the computer reach that point and is not hotter than 38ºC it works better, works smother, photoshop works faster, renders finish faster, video games run smoother etc, so i want to ask you guys if anyone knows exactly why this happens? is there a way to reach that state without previously heating a lot the computer? someone with the same issue? i've searching about this topic a lot but all i found is people who install SmcFanControl and complains about the sound of the fan or burn the graphic card playing WoW.

    any response will be appreciated, Thanks :) :D
  2. cynics macrumors G4

    Jan 8, 2012
    Your temps are WELL below CPU/GPU throttle temps. No performance differences should be discernible real world or via software (measuring clockspeed) at those temps.

    Assuming it's not psychological there is something else going on.
  3. GGJstudios macrumors Westmere


    May 16, 2008
    Those temps are completely normal. You don't need such apps to keep temps at a safe level, as OS X does that automatically.

    If you’re not already doing so, use iStat Pro (free) or iStat Menus ($16) to get accurate readings of your temps, fan speeds, etc., rather than relying on your sense of touch or sound. A forum member has posted a copy of iStat Pro that has been "tweaked" to enhance compatibility with recent OS X versions. You can download it here.
    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. (GPU Tjmax may vary with specific models.)(Source: Intel)
    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.
    The fans in Macs will spin faster as needed to keep temps at a safe level. If your fans are 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 on the back of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best. For Flash-related issues:

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