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Problem with 2560x1440 resolution via HDMI

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  • Problem with 2560x1440 resolution via HDMI

    hi everybody

    i've just bought a SAMSUNG S27A850D monitor, capable of 2560x1440 resolution it has DVI input

    i attached the HDMI output from my Acer 5742g notebook using an adaptor

    unfortunately the computer has an Optimus NVIDIA GT540M, and i use Bumblebee, the default driver is therefore the intel one

    the monitor is recognised and the EDID read, but the maximum resolution in the settings is 1920x1200

    adding a New Mode with xrandr i can get the full resolution:

    Code:
    xrandr --newmode "2560x1440_60.00"  241.50  2560 2608 2640 2720  1440 1443 1448 1481 +hsync -vsync
    xrandr --addmode HDMI-0 "2560x1440_60.00"
    xrandr --ouput HDMI-0 --mode "2560x1440_60.00"
    the problem is the display is badly pixelated and looks like the RGB subpixeling goes wrong (see the attached picture)

    the fonts are very small, smaller than the change in resolution can justify

    do you have an idea of what can go wrong?

    thanks in advance


  • #2
    Originally posted by papalagi View Post
    SAMSUNG S27A850D monitor, capable of 2560x1440 resolution it has DVI input
    i attached the HDMI output from my Acer 5742g notebook using an adaptor
    unfortunately the computer has an Optimus NVIDIA GT540M, and i use Bumblebee, the default driver is therefore the intel one
    the monitor is recognised and the EDID read, but the maximum resolution in the settings is 1920x1200
    adding a New Mode with xrandr i can get the full resolution:
    Code:
    xrandr --newmode "2560x1440_60.00"  241.50  2560 2608 2640 2720  1440 1443 1448 1481 +hsync -vsync
    xrandr --addmode HDMI-0 "2560x1440_60.00"
    xrandr --ouput HDMI-0 --mode "2560x1440_60.00"
    the problem is the display is badly pixelated and looks like the RGB subpixeling goes wrong (see the attached picture)
    My Motherboard (Asus P8Z77-M PRO, suitable for Ivy Bridge CPUs) manual says it supports the following video output for integrated Intel HD gfx:
    HDMI and DVI-D: max 1920x1200@60Hz
    RGB: max 2048x1536@75Hz

    Perhaps the board in your notebook has similar limitations. Or your HDMI-DVI adaptor may limit the resolution.

    Comment


    • #3
      Originally posted by sarimak View Post
      My Motherboard (Asus P8Z77-M PRO, suitable for Ivy Bridge CPUs) manual says it supports the following video output for integrated Intel HD gfx:
      HDMI and DVI-D: max 1920x1200@60Hz
      RGB: max 2048x1536@75Hz

      Perhaps the board in your notebook has similar limitations. Or your HDMI-DVI adaptor may limit the resolution.
      you gave me a hint with the resolution, in fact i can obtain a 2048x1152 (pretty good 16:9) at 60Hz without pixelation

      thank you!

      Comment


      • #4
        AFAIK, HDMI simply doesn't support 2560x1600. Even DVI only does in Dual-Link mode, and requires a Dual-Link cable which has approximately twice as many conductors as a regular DVI cable.

        Comment


        • #5
          HDMI does support 2560x1600, however, almost no monitors (or laptops) do. You can only run analog hdmi convertors up to 1920x1200, for resolutions above that you need an active component, which is more expensive to make. Extremely few monitors have this (I''ve seen some korean models with it, and I'm fairly sure that samsung does not have it).

          Your only option here is to run at a lower refresh rate, which should reduce the bandwidth enough to be usable (although not for gaming/anything fast paced).

          Unfortunatly support for this isn't documented very often... I contacted the manufacturer of the laptop I have, and they couldn't tell me whether or not it had a hdmi chip with this capability.

          Comment

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