Can't get Late 2013 13" rMBP to do 1440p HiDPI (Sierra)

Discussion in 'macOS Sierra (10.12)' started by BiscottiGelato, Jun 26, 2017.

  1. BiscottiGelato macrumors 6502

    Mar 11, 2011
    I just got myself a P2415Q 4K monitor and was looking forward to get more screen real-estate. Unfortunately I either get 3840x2160 Native, which have UI elements way too small, or 1920x1080 HiDPI with elements too big. If I try to do something in between, it just ends up getting not sharp. There's no 1440 HiDPI for some reason.

    I went through many hoops, went through a lot of posts on both MacRumors and on, resulting in the following attempts...

    1. Buying Accell mDP -> DP cable: It's claimed in a thread that this is one of the few properly DisplayPort 1.2 certified cable. But no, it didn't make any difference.

    2. SwitchResX with SIP disabled: Anything over 3840x2160 scaled is deemed 'Invalid'. (1440 HiDPI means 5120 x 2880 scaled down by 2...)

    3. Manually fiddle with DisplayProductID plists. I put in all the valid resolution between 1080p scaled and 1440p scaled with no avail. All did not appear in either SwitchResX nor RDP.

    4. Tried to do (3) with custom EDID that I modified to either 51Hz or 30Hz. They did successfully enable 51Hz 1080 HiDPi or 51hz 2160 Native. But none of the refresh rate combo enabled any HiDPI modes aside from 1080 HiDPI

    Is this a limitation of a Late 2013 13" rMBP? Something wrong with Sierra? Or am I missing something here? Very disappointed in Mac's support of 4K monitors. Please help.
  2. treekram macrumors 68000

    Nov 9, 2015
    Honolulu HI
    It's not difficult come across the following information on the web:

    1) 24" UHD is too small for most people at native resolution (3840x2160).

    2) The Intel Iris 5100, the GPU used in the late 2013 13" MBP's, is not very powerful by today's standards and officially only supports 3840x2160 at 30Hz (although people use SwitchResX to get 50Hz).

    3) HiDPI requires that the monitor support, natively, 2x the resolution you want to use. So 1440 HiDPI requires a monitor that supports 2880 pixels vertically, which a 3840x2160 monitor cannot do. You would need a 5K monitor to do 1440 HiDPI. Why were you expecting 1440 HiDPI from a UHD (3840x2160) monitor?

    It appears you tried resolution scaling and that wasn't satisfactory. I don't know if a better GPU (requires a new computer or an eGPU) would improve the quality or not (beyond the refresh rate).

    Maybe you can zoom in on an app-by-app basis. Otherwise, you should consider returning the monitor.
  3. BiscottiGelato thread starter macrumors 6502

    Mar 11, 2011
    My understanding is that HiDPi is create graphics asset at 2x the UI resolution, and then downscaling and displaying it at the monitor's native resolution thru anti-aliasing.

    The best example is the 13" MBP's screen. When 'More Space' is selected, it's displaying UI element at a size of 1680x1050 x2. Which means the UI elements are created at 3360x2100. It is then downscaled through anti-aliasing into the MBP's native resolution of 2560x1600. In fact, it tries to do this for a multitude of resolution

    Larger Text - Looks like 1024x640 (UI element rendered at 3x?)
    Default - Looks like 1280x800 (UI element rendered at 2560x1600 native)
    More Space 1 - Looks like 1440x900 (UI element rendered at 2880x1800 and downscaled to 2560x1600)
    More Space 2 - Looks like 1680x1050 (UI element rendered at 3360x2100 and downscaled to 2560x1600)

    As you can see, the resolution of the MBP monitor imposes no limit on whether the UI elements are rendered at beyond the monitor's resolution.

    So what HiPDi should do for a 4K monitor to look like 2560x1440 is to render the asset at 5120x2880 and then downscale it to display at 4K (3840x2160) resolution.

    I do agree and suspect that the limit is at the CPU and GPU's ability to render at such high resolution and then scale it back down to 4K resolution to display. On the other hand however there are many posts saying that HiPDi works much better pre-Sierra. I don't think it's absolutely clear whether the 3840x2160 @ 30Hz limit is a limit in terms of driving real pixels, or even just in rendering virtual pixels. It thus isn't clear to me whether this is a Sierra problem, or a hardware problem. Hence my question here to ask for other's experiences when it comes to Late 2013 rMBP on 4K monitors.

    Any more insight would be much welcomed. Thanks!
    --- Post Merged, Jul 8, 2017 ---
    I guess another way to word the question is: Whether all these problems are still applicable to Sierra, or if they are fixed and it's a HW limitation for the Late 2013 rMBP.
    --- Post Merged, Jul 8, 2017 ---
    Digging a bit further, it seems from this old post that Scaled HiDPI resolution is possible with the late 2013 rMBP against a 4k monitor... So still a Sierra SW problem then?
  4. treekram, Jul 8, 2017
    Last edited: Jul 8, 2017

    treekram macrumors 68000

    Nov 9, 2015
    Honolulu HI
    Some people (including myself) believe HiDPI applies solely to upscaling using integer multipliers (one person says "Half Pixels are a Lie"), others include resolution scaling (non-integer scaling) as part of HiDPI.

    In any case, 5K monitors were only supported in MBP's starting in 2016. So I do think trying to do 5K and then downscaling would be a stretch for the 2013 MBP.

    It looks like you've seen the posts which say resolution scaling was better in El Capitan. You might want to search and see if it's better in High Sierra - beta (it doesn't appear so from a quick look that I did).

    There's a person who rendered at 4K and then downscaled to 2K using SwitchResX - you might want to look at that.

    Minor update: Apple says the 2016 MBP (no distinguishing between 13" or 15") supports 5K, but Intel doesn't have 5K support in their iGPU's yet so I'm thinking that only refers to 2016/2017 MBP's with dGPU.
  5. BiscottiGelato thread starter macrumors 6502

    Mar 11, 2011
    Crazy discovery. If I set rotation to 90 degrees on my P2415Q MacOS lets me do 1440 x 2560 Scaled (Doesn't say Low Resolution). And things are crisp but at the size I want. So the hardware is capable of pushing this many pixels. Question is how do I get this working in Horizontal mode? (0 degrees)?
  6. ivan.ha macrumors newbie


    Jan 19, 2016
    Hong Kong
  7. yOr3z, May 29, 2018
    Last edited: May 29, 2018

    yOr3z macrumors newbie

    May 29, 2018

    Hey man, spent 6 hours straight on 2 days trying to figure out the exact same thing as you but with a MacBook Pro 13-inch, Mid-2012.

    Well, despite having trying everything possible I haven't really found any solution to my issue as it seems that in my case it is more of a hardware issue (not sure though as I surprisingly manage to natively support 3840 x 2160 @ 30Hz on my brand new LG UHD Monitor (27UK650) and also get 2560 x 1440 @ 60Hz, without HiDPi of course, all this over minDP-DP cable)

    Anyway, I just created an account to answer you as it seems that some guy managed to get something on that thread linked below. I hope it will help you and works.
    Please let me/us know if it worked, I am really curious to know if it's possible to get 2560 x 1440 HiDPi without the need of a 5k monitor.

    All the best,
  8. BiscottiGelato thread starter macrumors 6502

    Mar 11, 2011
    I forgot to say. High Sierra ended up fixing HiDPI at 30Hz for me. I bought SwitchResX and was able to push all the way to a usable 51Hz!

    But yeah, the laptop is noticeably slower once an external monitor is connected tho.

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7 June 26, 2017