Macbook Pro 2018 and External Monitors

Discussion in 'MacBook Pro' started by RamonRivera, Dec 2, 2018.

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  1. RamonRivera macrumors newbie

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    Nov 7, 2017
    #1
    I have a question to the Macbook Pro's experts, is it possible to run an external monitor using just the integrated graphics on the new Macbook Pros?

    If so what is the maximum resolution achievable? and how would the connection to the monitor would be achieved (thundebolt, HDMI).

    I ask this because I currently have a 2012 retina Macbook Pro and in order to run a external monitor it forces my Macbook to use the dedicated Graphic Card and I found that I have lower CPU performance when using the dedicated graphic card due to thermal throttling.
     
  2. unglued, Dec 2, 2018
    Last edited: Dec 2, 2018

    unglued macrumors 6502

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    #2
    Good question, I want to know the same as well if there’s a way to force integrated graphics to feed the external monitors. I’m planning to buy two 34” monitors for my new 2018 MBP and want to see the differences if fans run more or less.
     
  3. robvas macrumors 68030

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    #3
    On Macs that have both an integrated and a discrete GPU, the discrete GPU always drives any external displays connected to the system.
     
  4. unglued macrumors 6502

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    #4
    There’s no Terminal commands or utility to select it?
     
  5. robvas macrumors 68030

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    #5
    No, the hardware is wired that way. The built-in display is only connected to the iGPU on the 15" models.
     
  6. RamonRivera thread starter macrumors newbie

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    #6
    Is this also true when running in clamsell mode?
     
  7. robvas macrumors 68030

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    #7
    Of course, why would that change anything? The external video ports are not connected to the built-in GPU
    --- Post Merged, Dec 2, 2018 ---
    This is the same reason why if you have a 2011 with a bad GPU, if you do the 'fix' so that the GPU is ignored by the system, you can't use an external monitor. The connection just isn't there.

    Now if you are really, really set against not using the dGPU and still want to run an external monitor, you could buy one of those USB video adapters. Then you're using their driver as the 'video card' and your dGPU would still not be activated!
     
  8. unglued, Dec 2, 2018
    Last edited: Dec 2, 2018

    unglued macrumors 6502

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    #8
    Is that the same if dual monitors connect to a CalDigit dock (DisplayPort and Thunderbolt 3 ports) and the dock connects to the MBP USB-C port? By the way thanks for your help.
     
  9. robvas macrumors 68030

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    #9
    No. Those use the hardware signal over USB-C
     
  10. RamonRivera thread starter macrumors newbie

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    #10
    So if I connect my monitor via a thunderbolt dock I would be able to force the MacBook to use the integrated only?
     
  11. IdentityCrisis Suspended

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    Sep 9, 2018
    #11
    Caldigit dock uses the either igpu or dgpu in the laptop to produce the video signal over TB3.
     
  12. RamonRivera thread starter macrumors newbie

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    #12
    Am I wrong thinking that connecting via this dock you can choose which video card to use as to connecting directly only uses the dedicated?
     
  13. IdentityCrisis Suspended

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    Sep 9, 2018
    #13
    By default your MacBook Pro will automatically switch between the two graphics processors depending on how you're using your computer at the time.

    By way of example, your MacBook Pro uses the integrated Intel Iris Pro GPU if you're typing a document or browsing the web, but will switch to the dedicated NVIDIA GeForce GPU when you connect an external display or play a graphics-intensive game - basically whenever the extra graphics performance is needed.

    While this default behaviour is convenient and the best option for most users most of the time, as you have discovered there are times when it'd be better to bypass this.

    You have three options that give you some manual control over how the two graphics processors work:

    1. You can deselect Automatic Graphics Switching in System Preferences > Energy Saver. However, this actually enables the dedicated NVIDIA GeForce GPU by disabling the auto switching and does the exact opposite of what you want.

    2. Use the gfxCardStatus menu bar application to switch between your two graphics cards manually. This also lists which applications use the dedicated graphics so you have more control.

    Please note that while the gfxCardStatus application has been a saviour for many countless users over the years, that for some models the latest version is not actually the best one to use. I would install the latest version first (v2.3), but if you run into problems then try version 1.8.1 followed by version 2.1.

    3. Use gpu-switch to effectively do the same thing as the gfxCardStatus application, but switch between the integrated and dedicated GPU for the next reboot without the need of booting into macOS and running gfxCardStatus. However, setting this up is more for advanced users.

    The best way for you to find out if the integrated Intel Iris Pro GPU is capable of supporting your particular monitor is to try Option 2 above (i.e. use gfxCardStatus) to manually select it and see how you go.
     
  14. RamonRivera thread starter macrumors newbie

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    #14
    Yes I currently use Gfxcard status to force my computer to use the integrated because I ran into some trouble with some software I use to produce music was hogging the dedicated graphics card and making my computer throttle, that's the reason I want to know if its possible to drive an external monitor with the integrated as it produces less heat than the dedicated GPU and seeing the new macbook pros are prone to overheat I'm a little worried.
     
  15. robvas macrumors 68030

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    #15
    No. For what we are talking about, USB-C and Thunderbolt are interchangeable terms.
     
  16. likegadgets macrumors 6502

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    #16
    I run two LG UltraFine 5K displays directly connected to a MBP 2018 (Vega 20). Each monitor connects to one Thunderbolt port on each side of the MBP 2018 (the monitors include the thunderbolt cable). Both (as well as built in retina screen) all work great. Each monitor has USB c ports on the back where I connect external drives, scanner, etc) The Monitors power and charge the MBP.
     
  17. skirmisser macrumors member

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    Oct 2, 2012
    #17
    How does this setup perform in terms of UI fluidity and speed? Does everything more or less run at 60 fps? I have a Vega 20 and currently using an external 2560x1440 monitor. Should I expect a degradation in performance when driving 5K (in HiDPI mode - i.e 4x the pixel of 2560x1440) monitors?
     

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16 December 2, 2018