4k @ 60Hz?

Discussion in 'MacBook' started by slenpree, Mar 10, 2015.

  1. slenpree macrumors 6502a

    slenpree

    Joined:
    Apr 13, 2010
    Location:
    UK
    #1
    Looks like from the spec sheet the new MacBook supports a 4k external display, but there is no mention of the frame rate or from what adapter this is achieved with.

    So far apple only seem to have one digital USB-C adapter with HDMI, and the tech specs of this adapter say "up to 1080p".

    Any guesses what apple are talking about here ?
     
  2. RubberShoes macrumors regular

    Joined:
    Jun 30, 2007
    #2
    USB-C supports DisplayPort and if Apple is claiming 4K out I would bet a fair amount of money it's over that and not HDMI. Now the question is if it is DisplayPort 1.2 or 1.3. I'm betting 1.2. Either way framerate is going to suck. Intel's HD 5300 is barely above Ivy Bridge's HD 4000 performance and with a fanless design it won't take much time before throttling. We all know how Apple's last fanless system went.
     
  3. Mr Dobey macrumors 6502

    Joined:
    Aug 8, 2008
    #3
    straight from Intel, 3840x2160@60Hz 'additional cooling required'

    As much as I want it to support 4K60p it may be stuck at 30 due to the fanless design. I have the NVIDIA 650M Retina MacBook Pro which only supports 4K30p and it makes using a 4K TV as a monitor very straining.
     
  4. slenpree thread starter macrumors 6502a

    slenpree

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    #4
    Nice find. Sure , the gaming performance at that resolution and frame rate will suck but for desktop use I can't see it getting that hot really ?

    Let's hope those USB-C->display-port adapters arrive soon. Seems daft apple would brand this as "native" and not sell the adapter ??
     
  5. Mr Dobey macrumors 6502

    Joined:
    Aug 8, 2008
    #5
    Even without running anything, 3840x2160 at 60Hz 4:4:4 chroma Subsampling takes a whole lot of horse power. With the other graphics cards such as the NVIDIA 750M, 2GB VRAM is the minimum to present 60Hz, I don't know but I doubt the HD is pushing more than 2GB.
     
  6. danny_w macrumors 601

    Joined:
    Mar 8, 2005
    Location:
    Austin, TX
    #6
    I thought they said in the keynote that it could mirror but I did not hear anything about supporting other resolutions or extending the desktop. I don't think that is the intended purpose of this device.
     
  7. slenpree thread starter macrumors 6502a

    slenpree

    Joined:
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    Location:
    UK
    #7
    It's a MacBook - so I think it's intended purpose, for the most part, is the same as any other MacBook. I don't see why they would put lots of effort into improving dual display support in the last couple of OS X releases only to disable it on their new flagship model.

    Besides:

    "Dual display and video mirroring: simultaneously supports full native resolution on the built-in display and up to 3840x2160 pixels on an external display, both at millions of colours"

    Looks like the Core M chip supports 60Hz, but Intel recommend active cooling. I suspect apple are being quiet on the frame rate for a reason :(
     
  8. crsh1976 macrumors 6502a

    Joined:
    Jun 13, 2011
    #8
    Straight from the same spec page over at Apple's also:
    "Native DisplayPort 1.2 video output"

    DP 1.2 can theoretically handle 4k @ 60 Hz, but the culprit is the USB-C 3.1 port and its 5 Gbps bandwidth, that seriously limits the frame/refresh rate on an external display (for comparison's sake, a Thunderbolt 1's 10 Gbps lane cannot do 4k @ 60 Hz).

    So while Apple promises DP output, even at 4k resolutions, I can't see how the rMB be able to support 60 Hz..
     
  9. slenpree thread starter macrumors 6502a

    slenpree

    Joined:
    Apr 13, 2010
    Location:
    UK
    #9
    fair point. I could be wrong here, but USB 3.1 is 10Gbps like Thunderbolt 1? ( USB 3.0 is 5Gbps ), and also this is the speed of the port in USB mode, if it's "native display port 1.2", then presumabley the port can switch modes? but then again the new mac mini is displayport 1.2 and the first thing people noticed is the lack of 60Hz mode at 4k - this time due to the graphics chip because it's "Iris" and not "Iris Pro".
     
  10. slenpree thread starter macrumors 6502a

    slenpree

    Joined:
    Apr 13, 2010
    Location:
    UK
    #10
    Apple have now updated the support page about 4K support

    https://support.apple.com/en-us/HT202856

    No mention of the new MacBook, but nice to see the 13" MacBook Pro now supports 4k @ 60Hz :)

    •MacBook Pro (Retina, 15-inch, Late 2013 and later)
    •MacBook Pro (Retina, 13-inch, Early 2015)
    •Mac Pro (Late 2013)
    •iMac (Retina 5K, 27-inch, Late 2014)
     
  11. Mcdevidr macrumors 6502a

    Joined:
    Nov 27, 2013
    #11
    Im hoping it will do 60hz at 4k that would be nice. But if it does not, has anyone ran a 24 inch 4k Dell at say 2560x1440 and how does that look?
     

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