4K at 60Hz on 12" rMB Hack: Monitors, Cables & Adapters That Work

Discussion in 'MacBook' started by Hellhammer, May 24, 2016.

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  1. Hellhammer Moderator

    Hellhammer

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    #1
    Background

    [​IMG]


    USB-C has four high-bandwidth lanes that can be dedicated to either USB 3.1 Gen 1 (i.e. USB 3.0 - 5Gbps) or DisplayPort 1.2. In addition to these four lanes, USB-C has separate USB 2.0 and power lanes that are available at all times. Running 4K at 60Hz requires the bandwidth of all four lanes, which would limit USB to 2.0, and for some reason Apple has disabled this, leaving users with no proper 4K support. The MacBook supports 4K at 30Hz just fine, but most users have found this to be unusable since even moving the cursor has a notable lag.

    The Hack

    While this topic surfaces quite frequently, very few seem to be aware of a hack that enables 4K at 60Hz. The hack is called mac-pixel-clock-patch-V2 and user reports here indicate it works flawlessly and is smoother than the SwitchResX 50Hz hack since the panel can run at its native 60Hz refresh rate. Basically, the hack forces all four high-speed lanes to be dedicated to DisplayPort 1.2, meaning no USB 3.0, but USB 2.0 and power is still delivered assuming that the device/cable/adapter supports these.

    This Thread

    The purpose of this thread is to act as a general wiki database for user experiences and displays, cables and adapters that work. This is a wiki post, meaning anyone can modify this with the idea of keeping this as up to date as possible, so people can quickly find information and buy supported equipment.

    ---------------------------------------------------------------------------------------------------------------------

    Displays

    Lenovo ThinkVision X1 - 27" 4K IPS $669

    Reported to be working here. Has built-in USB-C port for video, data and charging, so no adapter needed. Built-in mic, camera and speakers work as well. However, the included USB-C cable does not work - see below for cables that have been confirmed to work.


    Adapters

    No specific adapters confirmed yet. This post mentions "a cheap USB-C to DisplayPort" working and technically all USB-C to DisplayPort adapters should work.


    Cables

    Apple USB-C Cable - NOT WORKING

    Only for charging - cannot be used for video or data.

    Monoprice USB 3.1 USB-C Cable 3ft - WORKING

    Confirmed to be working here.

    Belkin USB 3.1 USB-C Cable 3ft - NOT WORKING


    Supports charging and perhaps data, but no video as reported here.

    AUKEY USB 3.1 USB-C Cable 90cm - MIXED REPORTS


    One user is reporting it works, whereas another one reports it not working.

    Tenswall USB 3.1 USB-C Cable 3.3ft - NOT WORKING


    Reported here.
     
  2. w0rd3r macrumors regular

    w0rd3r

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    #2
    Asus PB287Q - 28" 4K TN $429

    I (w0rd3r) just tested it and it works at 1920 x 1080 HiDPI @ 60Hz, but no other scaled resolution like 1800p or 1440p. I used a Victsing adapter (http://www.amazon.com/dp/B0191PRS72/), so I'm not able to test a Clamshell mode, where I assume I'll be able to use every scaled resolution @ 60Hz.
     
  3. Hellhammer thread starter Moderator

    Hellhammer

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    #3
    Does HiDPI mean that it's running at 4K, but with everything scaled to 1080p? What was the resolution before you applied the patch? Just trying to make sure you're running it at max resolution.
     
  4. w0rd3r macrumors regular

    w0rd3r

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    #4
    Indeed, that is what I meant. Looking through the Monitor menu, I can clearly see he receives 3840 x 2160 @60Hz. But the MacBook makes it look like 1080p HiDPI (so it is scaled down to 1080p, but looks really sharp thanks to the 4K display).

    I forgot to add that I managed to run it 4K@60Hz only via mirroring.

    Before applying the patch, I ran the display at 2160p @30Hz. I wish I could use different scaled resolutions though. Can you? If you need screenshots of a system report, here they are
     

    Attached Files:

  5. rtr1985 macrumors 6502

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    #5
    Is this hack only enabled when connected to a 4K monitor and everything back to normal settings when disconnected?
     
  6. w0rd3r macrumors regular

    w0rd3r

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    #6
    I haven't noticed any difference whatsoever.
     
  7. rtr1985 macrumors 6502

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    #7
    USB 3 speeds without monitor?
     
  8. w0rd3r macrumors regular

    w0rd3r

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    #8
    Sure thing, here is a USB 3 enclosure with a mSATA SSD inside.

    Capture 4.jpg

    Capture 3.jpg
     
  9. rtr1985 macrumors 6502

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    #9
    Cool. Seems crazy not a default option rather than system hack. I'm no computer expert, though.
     
  10. tomislavf macrumors member

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    Nov 2, 2011
    #10
    It's probably not a system option because Apple doesn't want to explain why USB is running at 2.0 speeds when a 4k @ 60Hz display is connected.
     
  11. w0rd3r macrumors regular

    w0rd3r

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    #11
    Regarding the clamshell mode, I'll be able to test it in the upcoming weeks since I'll receive the KADI Port (with 2 USB-C).
    https://www.kickstarter.com/projects/thekadiport/the-kadi-port-a-macbook-essential
    So I'll use one with the charger and the other one with the DisplayPort adapter I mentioned earlier.

    I still don't know if I'll be able to use every scaled resolution just like an iMac or a MacBook Pro. If anyone can tell me which resolutions are available (as I said, for me it only works @1080p HiDPI @60Hz. Others are not available or @30Hz) it would be great!
     
  12. tomislavf macrumors member

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    #12
    Did you try using SwitchResX to create the custom resolutions?
     
  13. w0rd3r macrumors regular

    w0rd3r

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    #13
    I did not
     
  14. Hellhammer thread starter Moderator

    Hellhammer

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    #14
    Some Intel slides also mentioned that 4K may require additional cooling on Core M chips, so Apple might have disabled it to avoid excessive throttling and other heat issues.

    Give it a try. You should be able to run your 4K display at non-HiDPI resolutions as well, including 3840x2160 at 60Hz.
     
  15. w0rd3r macrumors regular

    w0rd3r

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    #15
    I'll see if I can, but I've not found anyone able to tell me if it had every option or not.
    1080p HiDPI is (unfortunately) useless for me, I'd like 1800p or 1686p.

    Do you know if it works only in mirroring mode for others as well as for me ?
     
  16. tomislavf macrumors member

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    Nov 2, 2011
    #16
    Well here's a screenshot where it's running without mirroring.

    [​IMG]

    From https://v2ex.com/t/277410
    --- Post Merged, Jun 1, 2016 ---
    For desktop use? Can't see it getting any hotter than playing a 3D game. Who knows... it's Apple :)
     
  17. 1080p macrumors 68020

    1080p

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    #17
    Thanks for the tag!
     
  18. rtr1985 macrumors 6502

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  19. in Cider macrumors member

    in Cider

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    Jan 28, 2016
    #19
    I just patched my rMB running 10.11.5 and I'm up and running at a glorious 3440x1440 @ 60Hz on an LG 34UC98 connected through an Aukey USB-C hub with HDMI out.
     
  20. tomislavf macrumors member

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    Nov 2, 2011
    #20
    Looking at that screenshot, the Dell P2415Q.

    I'm mostly interested in the LG 27UD88-W, a 4K USB-C display.
     
  21. ctyrider macrumors 6502a

    ctyrider

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    #21
    34UC98 is not a 4K display though. I didn't think you needed a patch to run this display at 60Hz.
     
  22. Outrigger macrumors 68000

    Outrigger

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    Dec 22, 2008
    #22
    Screen Shot 2016-06-05 at 12.11.25 PM.png
    its not a 4K display and you don't need a patch for it.
    --- Post Merged, Jun 5, 2016 ---
     
  23. in Cider, Jun 5, 2016
    Last edited: Jun 5, 2016

    in Cider macrumors member

    in Cider

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    #23
    While its not 4k, the resolution is still too high for native 60Hz on my rMB. 50Hz is the max OS X will allow until after the patch.
    --- Post Merged, Jun 5, 2016 ---
    I did need to patch to get to 60Hz on my rMB, otherwise the max I could get to work was 50Hz.
     
  24. tomislavf macrumors member

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    #24
  25. BeatCrazy macrumors 6502a

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    Jul 20, 2011
    #25
    How usable is 4K at 50Hz?
     
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