ExtremeTech thinks iMac Retina does 5K @ 30Hz

Discussion in 'iMac' started by mavere, Oct 24, 2014.

  1. mavere, Oct 24, 2014
    Last edited: Oct 26, 2014

    mavere macrumors member

    Jun 6, 2007
  2. QuarterSwede macrumors G3


    Oct 1, 2005
    Colorado Springs, CO
    This may be a separate issue from what they're specifically seeing but there is some major stuttering issues with it. However, a lot of older computers also have that issue on Yosemite so the consensus is that it's a window server issue.
  3. ra004e macrumors regular

    Jun 8, 2009
    Sorry no iPhone video, but tonight at apple store when I was playing with scaled resolutions above 2650 x 1440 ( best for display ) the windows did seem very choppy dragging them around.


    Just an observation, both my 2013 13" and 2012 15" inch rMBPs Yosemite has no issues dragging windows around with scaled resolutions above ( best for display setting )
  4. cycledance Suspended

    Oct 15, 2010
  5. McTaste macrumors regular


    Jan 21, 2014
    Hopefully someone can confirm this before my order is charged. I will cancel If the display can't do 60hz at 5k resolution.
  6. steve23094 macrumors 68020


    Apr 23, 2013
    I don't think they would make that claim without it being true so you had better cancel.

    Do you intend to run you iMac at 5k?
  7. tillsbury macrumors 65816

    Dec 24, 2007
    It's odd that they don't provide any indication of how they know this.

    When isn't the display running in 5k?

    In "best for display" mode, the logical pixel dimensions are the same as the old iMac. Then the system is adding additional information (in the fonts) and rendering it as a 5k display, and throwing it at the screen.

    Indeed (if it's anything like the rMBP) it renders higher than this. In the "looks like 3200x" mode, it's rendering a display window at 6400 pixels and then downscaling that to 5k.

    Are they saying that the display is always at 30Hz in HiDPI mode? I can't believe that from having used it.
  8. nomad421 macrumors member

    Jun 19, 2009
  9. mavere thread starter macrumors member

    Jun 6, 2007
    A 240fps capture of a simple, GPU-light animation (like just dragging a Finder window around the screen) would provide a straightforward answer.

    Quicktime allows frame-by-frame scrubbing of H.264, so someone only needs to upload the slowed-down version to Youtube or a filesharing service.
  10. rick987611 macrumors member

    Oct 28, 2008
    It is absolutely 60hz. I've seen 4k 30hz screens, it is obvious. This thing runs at a fluid 60hz.
  11. tillsbury macrumors 65816

    Dec 24, 2007
    More importantly, that tweet quotes his discussion with Cameron Rogers, who is likely to know. He says it's two DP1.2 channels running 60Hz (unlike what Anandtech is guessing).



    I agree. I was running one the other day at both "best for retina" and "looks like 3200" and no way was either of them 30Hz. 30Hz is a dog on a 4k display.
  12. EnderTW macrumors 6502

    Jun 30, 2007
    I saw that earlier. I was confused. The display is running at 5k at ALL TIMES. When you're doing retina resolution changes you're simply changing the scaling factor.

    I've seen 4k at 30hz it isn't 30hz
  13. McTaste macrumors regular


    Jan 21, 2014
    Yes I plan on utilizing the full resolution, not pixel doubled or scaled...
  14. johnnyturbouk macrumors 68000


    Feb 9, 2011
    on the yellow [oled] brick road to tech nirvana.
    This is an interesting development. I am glad I didn't pull the trigger and have waited to upgrade - hopefully an in depth Anand review should follow shortly
  15. houkouonchi macrumors regular

    Oct 31, 2005
    Window dragging and other choppyness asside, it would take all of 2 seconds of moving the cursor to tell if it was 30 or 60 Hz.

    I call BS on this. I think apple would claim that if that was the case as well.

    DP 1.2/tb2 is actually quick enough for 60Hz 5k @ 18 bit color though as CVT-R timings come in just around 940 Mhz against the 960 Mhz max pixelclock of DP 1.2
  16. WilliamG macrumors G3

    Mar 29, 2008
    I'm still unsure how Extremtech arrived at their 30hz conclusion...
  17. houkouonchi macrumors regular

    Oct 31, 2005
    I don't doubt that it is indeed 60hz but that is a pretty bad example. Honestly any browser based one isn't great as it doesn't always work on everything (notice how the page says windows).

    Anyway this is probably the best bet:

    It says 60Hz on my 30hz 4k display on linux; however, since its rendered at the right FPS you can easily tell if its skipping every other box or not even if it is detecting it incorrectly. That would be a better test.

  18. newbish, Oct 25, 2014
    Last edited: Oct 29, 2014

    newbish macrumors member

    Oct 25, 2014

    First post at MacRumors! Registered to join in the conversation on the new retina iMac as i've just received mine yesterday.

    I've tried borderlands the pre-sequel, set it to high settings and capped at 60FPS. I'd say it is 60FPS for sure as I have captured it on my iPhone w/ 60FPS mode. Really butter smooth!

    edit: testufo appearing as 60Hz/FPS too

    edit2: reuploaded on youtube my borderlands video. now that youtube supports 60FPS uploads. https://www.youtube.com/watch?v=RdwSuPiRSVY
  19. dlewis23 macrumors 6502a

    Oct 23, 2007
    You can't go by the one in store because they all have the m290x and there is a problem with performance and the m290x.

    They say the GPU is limited to DisplayPort 1.2 in there article and thats where I think they came to there 30 Hz conclusion.

    The panel is 60 Hz doesn't matter what scaled mode you are in ExtremeTech is extremely wrong. It's very easy to tell that its not 30 Hz. Look at any YouTube video of a 30 Hz 4k display and then drag a window around and you can see its 60 Hz.
  20. Seramir macrumors member


    Nov 10, 2006
    This is a HUGE make or break on deciding to buy the Retina iMac.

    Hopefully we can get some real undeniable answers, besides people just saying it's 60Hz because it seems smooth to them.
  21. macmee Suspended


    Dec 13, 2008
    Yep, I have a 4k monitor that came with DP1.2 disabled so it was defaulted to 30hz. Terrible experience, I enabled DP1.2 right away and 60hz was a huge improvement.

    For $4,000 (with upgrades) these machines especially couldn't be 30Hz, it would be a disaster for Apple.
  22. 5iMacs macrumors regular

    Oct 25, 2014
    Yes there really is no doubt, if you have access to a 5k iMac just go here and see the 60Hz in action:

  23. shokunin macrumors regular

    Jun 7, 2005
    Mine says 60fps, did different tests, each saying 60fps. the 30hz would look way choppy a quick scroll in a long text document shows complete fluid motion, no choppiness at all.

    Test was done at Retina "best" scaling 2560x1440.


    Also 60hz/60fps in the highest scaling mode 3200x1800.
  24. macmee Suspended


    Dec 13, 2008
    I don't believe you, you're probably a liar. Please mail me your 5k iMac and I'll do the test myself. I'll make sure to send it back after :)

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