Two 2560x1440 monitors and rMBP. How to best set up?

Discussion in 'MacBook Pro' started by kkozmic, Aug 11, 2012.

  1. kkozmic macrumors newbie

    Aug 11, 2012
    I'm planning to get two external (non-Apple) monitors, both running 2560x1440 resolution.

    After doing some research I'm however much more confused than I was when I started.

    Basically the question is - is this setup going to work at all? Can rMBP work with two monotors like that? I know it can support that resolution on Thunderbolt display but how about plain vanilla HDMI screens?

    Does anyone run a setup like that? What cable (and/or Thunderbolt --> HDMI converter) to use?

    Most if not all of these I found on ebay advertise support for up to 1920x1080 resolution, but what about 2560x1440?
  2. tenshu2k macrumors member

    Oct 13, 2002
    I have my rMBP running with a single 2560x1440 monitor with a dual link dvi cable + rMBP display.

    I almost feel it a bit of a waste on dual monitors.
  3. phyrexia macrumors 6502a

    Sep 3, 2010
    As I understand, you can go TB->DVI/DP/Whatever->Monitor One and HDMI->2nd Monitor Two.
  4. maxwelltech macrumors 6502


    Dec 29, 2011
    Irvine, CA, USA
    It will work. The HDMI port will only work for displays up to 1920x1200, so you need to use the two Thunderbolt ports for connecting to your external display. Buy two Mini DisplayPort to dual link DVI connectors (or full-size DisplayPort), connect them, and they should work. Don't use the HDMI port, it will not support 2560x1440.
    MDP to dual link DVI:
    MDP to DisplayPort (not sold by Apple):
  5. houkouonchi macrumors regular

    Oct 31, 2005
    It will be fine but you probably will want a USB hub as all the display port -> dual link DVI adapters require USB for power.
  6. jtus macrumors member

    Jul 12, 2007
    I have run two dell monitors on my MBP with one connected to a Apple adapter pluged into the thunderbolt port and the other hooked to a usb to vga adapter purchased from BestBuy ( Mad Catz - UV150 Graphic Adapter - USB ) for $55.00.
  7. 725032 Guest


    Aug 5, 2012
    good luck with that... the resolution issues are going to be horrible
  8. macuser2134 macrumors member

    Feb 15, 2012
    Don't understand why this HDMI restriction. The HDMI interface is buffered by a Parade PS8401

    Which is capable of higher 4k and 2k resolutions. The Input to this HDMI chip seems to be a DisplayPort channel. If we plug a display into a DisplayPort (when the Thunderbolt port is being used as a miniDisplayPort). Well... that plug supports the higher resolutions. Putting this restriction on the dedicated HDMI port just doesn't seem very logical.

    Perhaps there is a total bandwidth shared across all 3 ports. So the HDMI DisplayPort channel was designated with whatever remaining bandwidth was left over after the 2 other channels. I for one would like to see a future kext hack (a patch of the video driver). The Thunderbolt port is more valuable for accessories for example the GigE adaptor. Which of course cannot be daisy-chained therefore occupying 1 ThunderBolt port each.
  9. houkouonchi macrumors regular

    Oct 31, 2005
    I have never seen a computer able to drive something over HDMI over 1920x1200 nor have I ever seen a computer monitor which would take > 1920x1200 over HDMI. The newer spec handles it but I know on linux it always showed up as single link DVI (max 165 Mhz pixelclock).
  10. macuser2134 macrumors member

    Feb 15, 2012
    Hmm. This is a good point. In fact, DisplayPort and HDMI were developed as seperate standards. So not all of the different operating modes necessarily match up exactly. Yet, however much I look into these specifications on Wikipedia, there seems no pressing technical restriction. Just that you need to plug in a "high speed" HDMI cable to support the necessary bandwidth (340 Mhz). The allowed displayed resolutions do match up. And like the Parade spec says, its HDMI 1.4b, which means by definition it must support those higher 2k and 4k operating modes to be compliant to the HDMI certification.

    So we are really only left tracing backward along the displayport channel to before the Parade controller gets involved. I mean, to find a bandwidth restriction it would have to be in the Intel HD4000 or the Nvidia 650m graphics. And yes, I don't really understand why other consumer devices cannot support this if they are at both ends HDMI 1.4 compliant devices (with a high speed HDMI cable in-between!!??!).
  11. houkouonchi macrumors regular

    Oct 31, 2005
    I tell you what. I have linux which actually tells me the bandwidth available of things on my macbook pro. I will hook it up to a TV and check out what it says the max bandwidth is over HDMI. I know over display port (via a DP -> dual link DVI adapter) it was 475 Mhz.
  12. macuser2134 macrumors member

    Feb 15, 2012
    Any luck?
  13. hvgotcodes macrumors member

    Feb 2, 2011
    I think your best bet is to just get 2 thunderbolt displays. You can chain them together.

    I have something similar (one cinema, one thunderbolt) and it works ok. I thought I could plug the mini hdmi into the thunderbolt display, but even though physically its possible the cinema wont work in this configuration. So I plugged the mini display of the cinema into the second thunderbolt port.

    Beware the heat!!! My office is noticeably hotter with an extra 500 watts of power being used in it...
  14. Stetrain macrumors 68040

    Feb 6, 2009
    Which specific monitors are you looking at? If they have Displayport inputs (I know the Dell Utrasharps do) then the best way to go would be two Miki-Displayport to Displayport cables.
  15. houkouonchi macrumors regular

    Oct 31, 2005
    Yeah. Sorry I totally forgot to do this:

    The apple internal LCD is display port:

    (II) Aug 17 03:50:08 NVIDIA(GPU-0): Skipping Power Connector Check.
    (II) Aug 17 03:50:08 NVIDIA(GPU-0): DFP-3: DisplayPort revision 1.1
    (II) Aug 17 03:50:08 NVIDIA(GPU-0):     Maximum link rate:   2.70 Gbps per lane
    (II) Aug 17 03:50:08 NVIDIA(GPU-0):     Maximum lane count:  4
    (II) Aug 17 03:50:08 NVIDIA(GPU-0):       Maximum pixel clock: 475.248 MHz
    (II) Aug 17 03:50:08 NVIDIA(GPU-0):     Enhanced framing:    Supported
    (II) Aug 17 03:50:08 NVIDIA(GPU-0): Display (Apple Color LCD (DFP-3)) does not support NVIDIA 3D
    (II) Aug 17 03:50:08 NVIDIA(GPU-0):     Vision stereo.
    (--) Aug 17 03:50:08 NVIDIA(0): Connected display device(s) on GeForce GT 650M at PCI:1:0:0
    (--) Aug 17 03:50:08 NVIDIA(0):     Apple Color LCD (DFP-3)
    (--) Aug 17 03:50:08 NVIDIA(0): Apple Color LCD (DFP-3): 480.0 MHz maximum pixel clock
    (--) Aug 17 03:50:08 NVIDIA(0): Apple Color LCD (DFP-3): Internal DisplayPort
    (--) Aug 17 03:50:08 NVIDIA(0): Apple Color LCD (DFP-3): Native FlatPanel Scaling is not
    (--) Aug 17 03:50:08 NVIDIA(0):     supported
    (--) Aug 17 03:50:08 NVIDIA(0): Apple Color LCD (DFP-3): DFP modes are not limited to 60 Hz
    (--) Aug 17 03:50:08 NVIDIA(0):     refresh rate
    (--) Aug 17 03:50:08 NVIDIA(0): Apple Color LCD (DFP-3): DFP is internal to notebook
    The HDMI appears to be a single link (165Mhz max bandwidth) connection like I expected:

    (--) Aug 17 03:53:42 NVIDIA(0): Connected display device(s) on GeForce GT 650M at PCI:1:0:0
    (--) Aug 17 03:53:42 NVIDIA(0):     PANASONIC-TV (DFP-2)
    (--) Aug 17 03:53:42 NVIDIA(0):     Apple Color LCD (DFP-3)
    (--) Aug 17 03:53:42 NVIDIA(0): PANASONIC-TV (DFP-2): 165.0 MHz maximum pixel clock
    (--) Aug 17 03:53:42 NVIDIA(0): PANASONIC-TV (DFP-2): Internal Single Link TMDS
    (--) Aug 17 03:53:42 NVIDIA(0): PANASONIC-TV (DFP-2): Native FlatPanel Scaling is supported
    (--) Aug 17 03:53:42 NVIDIA(0): PANASONIC-TV (DFP-2): DFP modes are not limited to 60 Hz
    (--) Aug 17 03:53:42 NVIDIA(0):     refresh rate
    (--) Aug 17 03:53:42 NVIDIA(0): PANASONIC-TV (DFP-2): DFP is not internal to notebook
    I really don't see how this thing will support > 1080p at a normal 60 Hz progressive refresh.
  16. macuser2134, Aug 17, 2012
    Last edited: Aug 17, 2012

    macuser2134 macrumors member

    Feb 15, 2012
    Ahh great to see that. Unfortunately its hard to see from that log if the restriction is indeed a hardware one or a software one. Aparrently the kernel and nvidia drivers are still improving on linux and aren't fully developed yet. So its still perhaps possible to be a coincidental lack of software support on both operating systems.

    Am I correct in thinking that Apple don't officially state anywhere the version of HDMI that their product is actually compliant with? They just simply say its got an HDMI port. Which reveals absolutely nothing to us.

    On the internet I found this 1 guy who suggested a way to test if the rMBP is HDMI 1.4 compatible:

    The suggestion is to try using SwitchResX rather than rely on OS X alone. I'm not sure of the validity of the claim. But it certainly would be possible to test out the hypothesis. By firing up SwitchResX program. Of course you also would need (perhaps most people don't have these): A high resolution display with HDMI input that is bigger than >1920x1200. Otherwise maybe an "HDMI dongle" to convert the HDMI to DVI or something.
  17. macuser2134 macrumors member

    Feb 15, 2012
  18. Galatian, Nov 15, 2013
    Last edited: Nov 15, 2013

    Galatian macrumors 6502


    Dec 20, 2010
    I really hate to resurrect such an old thread, but I'm running into the same kind of problem. I bought myself a nice Korean Display (I in fact believe it's the same one used in the iMac, as it also has it's glass front fused to the display) which run's perfectly fine on 2560x1440 over the Displayport (using Mini-DP to DP cable). Now I'm planning on getting two more of these screens and I want to run one of them of the HDMI port on my 2012 13" rMBP, but it will only allow 1920x1200@60 Hz.

    I already checked the screen and it supports HDMI 1.4 fine. I can run the Display at 2560x1440@60 Hz on my Windows gaming rig through HDMI, so it is neither a limitation by the monitor or the cable.

    The new late 2013 13" rMBP product sheet specifies that it can run HDMI display up to a 4K resolution, but the HD4000 was already capable of doing this in my model as was the ParadeTech PS8401A HDMI Jitter Cleaning 3 Gbps HDMI repeater.
    Some people on the Apple support forum say they can get a custom resolution with switchresx to work @40 Hz, but I've been out of luck so far/not really sure how to work the custom profile.

    Also I did create a custom override profile for the screen, so Mac OS X 10.9 does not think it is a television and hence setting the color option to YCbCr. I can run the display at the full RGB color gamut, but that didn't fix my problem with the resolution.

    All in all it just seems to be a software limitation/bug from Apple at this point and I would like to know if anybody has been successful thus far? I'm really not going to get a new MacBook just so I can use the third screen at it's full resolution just because Apple can't seem to be bothered with getting their machines work with other monitors. I have to say when I look how many threads with similar subjects are to be found via google, it's seems to be piss-poor external monitor support from Apples side unless one uses their Thunderbolt display.

    Edit: Actually I just got the Display to work with SwitchresX...One just has to make sure to stay beneath 160 Hz pixel refresh rate, as this seems to be the limiting factor. Happy camper now, just wished it would work out of the box and not with this "heavy modification".

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