New 2017 27" only using Dual Cores to render?

Discussion in 'iMac' started by davetwo, Jul 1, 2017.

  1. davetwo macrumors newbie

    Joined:
    Nov 29, 2016
    #1
    in Cinebench I ran a test after finding my new 27" imac not so quick to render in Cinema 4d and found that it only reads as having 2 cores (4 threads). I've bought it as a quad core machine.... what's going on????
     
  2. T'hain Esh Kelch macrumors 601

    T'hain Esh Kelch

    Joined:
    Aug 5, 2001
    Location:
    Denmark
    #2
    Where do you see that it only uses 2 cores - Cinebench or Activity Viewer?
     
  3. davetwo thread starter macrumors newbie

    Joined:
    Nov 29, 2016
    #3
    Cinebench (and when the machine is listed in Team Render in Cinema4D).Screengrabs attached
    Screen Shot 2017-07-01 at 17.40.39.png Screen Shot 2017-07-01 at 17.30.01.png
     
  4. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #4
    This is probably a bug in Cinebench, as your i5 obviously has four physical cores. Note they report 2x the threads per core for both i5 and i7. This only applies to i7. They probably forgot to report it differently for hyperthreaded vs non-hyperthreaded CPUs. You can examine what Cinebench actually does by watching with Activity Monitor. Start up AM and select either Window>CPU Usage and/or Window>CPU History, then run Cinebench. This will show what's happening on each core. Cinebench is probably using all cores but reporting it incorrectly.
     
  5. T'hain Esh Kelch macrumors 601

    T'hain Esh Kelch

    Joined:
    Aug 5, 2001
    Location:
    Denmark
    #5
    Check the usage in Activity Monitor. Cinebench is known to report the wrong number.
     
  6. EugW macrumors 68020

    EugW

    Joined:
    Jun 18, 2017
    #6
    Right. The 7600K only has 4 threads. It's 4 cores for 4 threads, not 2 cores for 4 threads, so it's a bug.
     
  7. davetwo thread starter macrumors newbie

    Joined:
    Nov 29, 2016
    #7
    Yeah - the activity shows all 4 cores. Must be a bug.
    Still surprised by the low score though ... it comes in around 615... substantially less than my 2016 MBP (around 730).
     

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