4K resolution output from rMBP... pre-Haswell?

Discussion in 'MacBook Pro' started by bill-p, Jul 1, 2013.

  1. bill-p macrumors 68000

    Jul 23, 2011
    I think this question was posed at some point, because it's clear that some of us would like to take advantage of that massive resolution whenever displays that carry it become available on the market at some point.

    And it seems like 10.9 DP does include preliminary support for it. In fact, it works even via HDMI, so we can save the Thunderbolt buses for other peripherals.


    Source: http://blog.joemacirowski.com/archives/1242

    Very nice! I think I may end up keeping my rMBP 15" and skip the Haswell update after all. Saving up for a 4K Retina Display (or whatever Apple may call it) looks like a more logical step.

    It's nice to know a machine I bought 11 months ago is still going to be useful in the future.
  2. Gav2k macrumors G3


    Jul 24, 2009
    I'm sure it's a mistake as you need tb2 port or hdmi 2.0
  3. dusk007 macrumors 68040


    Dec 5, 2009
    What does that mean? Doesn't it already work in 10.6/7/8.
    It is just a higher res and only for 60 hz you need DP 1.2 but for low refresh rate you always could go much higher.
    The maximum resolution of ivy bridge graphics (aka HD 4000) was 4096x4096 which is double standard 4K. The only real issue has always been to somehow deliver the output to a display. Even DP 1.2 is on one port not capable of actually pushing that.
  4. bill-p, Jul 1, 2013
    Last edited: Jul 1, 2013

    bill-p thread starter macrumors 68000

    Jul 23, 2011
    Not necessarily. rMBP 2012 (and I'd guess the early 2013 models as well) have HDMI 1.4, which does support 4K (3840 x 2160) at up to 30Hz, or 4096 x 2160 at 24Hz.

    Source: http://en.wikipedia.org/wiki/HDMI#Version_comparison

    If not that, then even Thunderbolt 1.0 can support 4K at 60Hz because it has far more than enough bandwidth for that. In fact, specs say DisplayPort 1.1a can do 4K at 60Hz even for 10-bit colors... if Apple decides to make the next Cinema Display that good.

    Specs say the current rMBP can support 4K. We're just getting a confirmation now with 10.9 DP.

    Nope. If you plug in a HDMI 1.4 cable to a rMBP 15" under Mac OSX, it'll always limit the output to max 1920 x 1200. I tried.

    But under Windows, it could go to 2560 x 1600, so the potential was always there. It just seemed like Apple purposefully limited it.

    And DP 1.2 is not necessary. DP 1.2 just allows 4K over a "single cable", but that doesn't mean you can't output 4K over 1.1a with a dual cable. It'd just bog your 2 Thunderbolt buses. More info:

    Now that we know HDMI can do it, too, I guess some of us can make do with 30Hz and still have the 2 Thunderbolt buses for other things.
  5. bill-p thread starter macrumors 68000

    Jul 23, 2011
    And here come displays that will make use of that monstrous resolution (and the extra scaling options offered):


    Interestingly, only one DisplayPort input, so I'd guess that has to be DP 1.2. But there is HDMI inputs as well. Presumably for 4K @ 30Hz for HDMI 1.4 specs since HDMI 2.0 specs are not even finalized yet.

    Note after reading PR texts: yep. DP 1.2 and HDMI 1.4.

    PR can be read here:

    So it looks like old rMBP isn't out of the running yet. But it also looks like Apple won't be able to push a 4K Retina Display for cheap.
  6. priitv8 macrumors 68040

    Jan 13, 2011
    To what monitor did you connect it? A HDTV or a 4K display? Also, did you use SwitchResX to set the display mode?
  7. bill-p thread starter macrumors 68000

    Jul 23, 2011
    A 2560 x 1600 monitor that supports HDMI input (1.4).

    Yes, tried SwitchResX. No dice. Max resolution under 10.8.4 is just 1920 x 1200.

    Under Windows in Bootcamp, the monitor was recognized as a full 2560 x 1600 monitor, and I could also output full resolution and refresh rate just fine.
  8. priitv8 macrumors 68040

    Jan 13, 2011
    OK. So Apple Thunderbolt Display achieves higher resolutions only thanks to DisplayPort?
    Sadly I have no such monitor to give it a try.
  9. bill-p thread starter macrumors 68000

    Jul 23, 2011

    2560 x 1600 requires either dual-link DVI or DisplayPort.

    Single-link DVI only supports max 1920 x 1200, and I suspect that's what OSX up to 10.8.4 is limiting the HDMI 1.4 port on the rMBP to. There is no such limitation under Windows.

    Technically HDMI 1.4 should be able to go up to 4K (3840 x 2160) at 30Hz.

    Now I'm wondering if the 13" rMBP can do the same.

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