Exporting video causing very high CPU temps?

Discussion in 'iMac' started by alexmshore, Jul 12, 2016.

  1. alexmshore macrumors member

    Joined:
    Nov 3, 2011
    Location:
    UK
    #1
    Hi there,

    I've just picked up a new 5k iMac i7. I am seeing unbelievabley high CPU temps while exporting video with Screenflow, all cores between 95-100°C. I have been in touch with Apple support and they say that temperature is certainly not normal.

    I'm curious if anyone else is using this machine and noticed high temperatures while doing cpu intensive tasks? What temps do you see with 90% cpu usage?

    Thanks, Alex
     
  2. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #2
    Whats the fans doing? at 95-100'c the should sound like a hoover.
     
  3. alexmshore thread starter macrumors member

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    Nov 3, 2011
    Location:
    UK
    #3
    Exactly that. That's what first drew my attention to it, they ramp up to around 2800-3000rpm.
     
  4. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #4
    95-100°C sounds quite normal for video exporting, which is basically encoding the video and taxing all the cores. The Tj Max of Skylake desktop CPUs is 100°C, which is the point where the CPU starts to throttle itself to prevent overheating.
     
  5. Samuelsan2001 macrumors 603

    Joined:
    Oct 24, 2013
    #5
    Well Apple support agree it's not normal what more do you need return for repair or replacement.
     
  6. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #6
    Yup, that's normal. You're working the CPUs quite heavily which is causing the high temps. If it gets too hot, the CPU will start throttling itself. We're talking about about an All in One computer in an incredibly thin design. The heat builds up quickly when pushing the CPU
     
  7. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #7
    This is normal and not a cause for concern. Transcoding "long GOP" codecs such as H264 is inherently CPU-intensive and cannot be meaningfully accelerated by a GPU. It is a compute-bound multithreaded operation. Software which supports Intel's Quick Sync can leverage this and often results in much faster transcode performance and lower CPU temps. FCPX uses this where applicable, Adobe apparently just added this to Premiere CC (Windows only), but I doubt Screenflow uses that.

    On my 2015 top-spec iMac 27 if I transcode 4k H264 to ProRes (which cannot use Quick Sync for encoding), it saturates all CPU cores and the core temps are often around 95-98C and fan speed is about 2800 rpm. If I transcode to single-pass 1080p H264, it apparently uses Quick Sync and CPU core temp is about 60C and fan speed is around 1200 rpm. Those temps provided by iStat Menus.
     
  8. alexmshore thread starter macrumors member

    Joined:
    Nov 3, 2011
    Location:
    UK
    #8
    Thanks everyone for your replies. Makes sense, I think I will give things a go in FCPX and go from there.
     
  9. cynics macrumors G3

    Joined:
    Jan 8, 2012
    #9
    The encode process is only limited by the maximum speed of the processor. 100% usage will happen on all processors, the only difference is speed (faster processor = faster export). And 100% usage will = HOT.

    I'm currently doing the same thing and I'm looking at 93 degrees celsius @ 100% usage on an i5.

    If it helps put your mind at ease I have at the very least 800 hours/33 days (~200 projects @ 4 hours each) of this on this processor with no ill side effects.
     
  10. junipho macrumors newbie

    junipho

    Joined:
    Mar 19, 2017
    #10

    I always use screenflow. Try to use a different temp reading app...... I had my temp reading at around 90 degrees celcius originally when I was exporting from screenflow. Which definitely wasn't normal (the reading was incorrect). I changed apps, and got a correct reading of around 60 degrees celcius.

    I now use "MONIT" and "FANNY".... both these apps are great and can't fault them. They sit in your mac notifications bar making the very convenient. You need both, MONIT for full statistic readings of your mac and FANNY for temp reading and fan speed.

    Bye
     
  11. Fravin macrumors regular

    Fravin

    Joined:
    Mar 8, 2017
    Location:
    Rio de Janeiro, Brazil
    #11
    No it's not that normal. The 2015 i7's iMac uses an 6700k chip. Regarding Intel the normal temperature should be around 60C.

    https://ark.intel.com/products/88195/Intel-Core-i7-6700K-Processor-8M-Cache-up-to-4_20-GHz

    It could run easily at 100C in the North Bridge Chipset. But not in the CPU's core.
     
  12. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #12
    That page mentions "Tcase" max of 64C, which is a laboratory measurement Intel makes when the CPU is developed. It is totally different from the typically reported "Tjunction" temperatures by utilities:

    http://www.intel.com/content/www/us/en/support/processors/000005597.html

    The max Tjunction temp for an i7-6700K is 100C, which is listed in Intel's datasheet on page 93 (PDF): http://www.intel.com/content/dam/ww...sktop-6th-gen-core-family-datasheet-vol-1.pdf

    We know from actual testing the i7-6700K in the 2015 iMac 27 often hits 90C or a bit more and does not usually thermally throttle under that load:

    [​IMG]

    Above from Max Yuryev test of 2014 vs 2015 iMac 27:
     

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