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papadeltasierra

1 Rookie

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20 Posts

2766

September 17th, 2019 00:00

Optiplex 9020, CentOS7, 4K TV - how?

I have an OptiPlex 9020 hooked up via displayport to an LG 4K TV but cannot get a 4K picture. What I know is that: 1/ The TV reports 4K capability via EDID 2/ xrandr indicates that the TV is connected via 'HDMI-1' and not 'DP-1' (there is no true HDMI port on the Optiplex!) 3/ xrandr reports available resolutions up to 1920 but nothing beyond. 4/ I've tried using xrandr newmode/addmode but enabling the new mode results in the old "configure crtc 0 failed" error. Someone managed to get 4K out of this PC previously but didn't note down how and clearly didn't make their change permanent so having had to move the system, no 4K now :-(. Suggestions?

speedstep

11 Legend

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47K Posts

September 17th, 2019 11:00

CENTOS is not supported here.

HDMI 1.4 does not support 4k.

Requires at least GT1030 GPU.

https://www.dell.com/en-us/work/shop/pny-geforce-gt-1030-graphics-card-2-gb-gddr5-low-profile/apd/a9763687/graphic-video-cards

 

 

papadeltasierra

1 Rookie

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20 Posts

September 18th, 2019 01:00

This does support 4k and last night I figured out how. The first issue is that the onboard Intel HD4600 graphics are capable of 4k/60Hz BUT ONLY if the DisplayPort is connected to a DisplayPort capable monitor. If instead you connect to an HDMI monitor then the DisplayPort switches to HDMI 1.4 mode and HDMI 1.4 cannot support 4k/60Hz - but it CAN support 4k/24Hz (see ark.intel.com, search for your processor for details). Second issue is that CentOS/X-desktop does not extract 4k settings from the TV's EDID data so you have to teach CentOS/X-Desktop that the monitor support 4k/24Hz. You can do this by first decoding the EDID data from the TV, which may tell you everything and if required using 'cvt' to generate a modeline using 'cvt 3840 2160 24.0'. Be careful because the monitor/TV might require different hsync/vsync polarities to the default cvt output but the EDID will configrm this. Now you can use the xrandr commands 'newmode' to add the modeline for '4k/24Hz', 'addmode' to tell the HDMI interface about this new mode and 'output/mode' to set this mode. If everything works, you then create a file in /usr/share/X11/xorg.conf.d to make your changes permanent (refer to 'man xorg.conf' for info and be sure to check that you can ssh into a terminal to fix any errors which might make the main monitor totally blank before you start!). The result of this is the Optiplex 9020 with a 4k/24Hz display; nice for a large screen 'pretty staic' display.

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