Arch Linux

Fitzwilliam

Member

Registered: 2010-12-23

Posts: 21

[SOLVED] I know my monitor supports 1080p72, but I can't convince Xorg

Hi,

So, I just came back to Arch after a couple of years in Fedora. Everything's gone well so far, and I've decided to do something that I've been doing in Windows for a while now: overclock my monitor.

I have a Dell S2440L, with a maximum advertised resolution of 1080p60. However, I know that it can actually support up to 1080p72; I've had that set as a custom resolution for years in my Windows partition with no issues. So, I took the timings that I know work in Windows and used an online converter to convert them to an xrandr modeline, and then following the Wiki's guide on how to add a custom resolution using xrandr. Unfortunately, it was at that point that I hit a wall. Observe:

[fitz@oculus ~]$ xrandr --newmode "1920x1080_72.00" 160 1920 1950 1990 2035 1080 1083 1087 1092 +HSync +VSync
[fitz@oculus ~]$ xrandr --verbose --addmode HDMI-0 1920x1080_72.00
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  39
  Current serial number in output stream:  40

Being a good little boy, I scoured the Xorg man pages, the Wiki, the Forum, and the Internet in general for solutions, and I have tried just about everything short of fiddling with the kernel, which frankly scares me.. No matter what I do, either nothing happens, or Xorg refuses to load. My conf file:

Section "Screen"
        Identifier      "Screen0"
        Device          "Device0"
        Monitor         "Monitor0"
        DefaultDepth    24
        SubSection      "Display"
                Depth           24
#               HorizSync       30-83
#               VertRefresh     55-75
#               Modeline        "1920x1080" 160 1920 1950 1990 2035 1080 1083 1087 1092 +hsync +vsync
        EndSubSection
EndSection

If I uncomment any of those three lines, Xorg won't load. I've also tried using "Modes" instead of "Modeline" and putting them in "Screen", rather than "Display". This kind of setup seemed to work for a lot of other people, and Xorg configuration documentation seems distressingly thin on the ground, so I'm not sure what I'm doing wrong.

If anyone could point me in the right direction, that would be lovely.

SYSTEM

Monitor: Dell S2440L
GPU: NVIDIA GTX 780
Display Driver: nvidia 364.16-3
Xorg: xorg-server 1.18.3-1
DE: KDE 5 w/ SDDM (Doubt that this matters, but who knows...)

Last edited by Fitzwilliam (2016-04-22 17:30:23)

Lone_Wolf

Member

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 11,920

Re: [SOLVED] I know my monitor supports 1080p72, but I can't convince Xorg

Display Driver: nvidia 364.16-3

Nvidia driver has it's own method to define/select resolution modelines, check usr/share/doc/nvidia/README .
It should have all the details about how they do things.

---

Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

(A works at time B)  && (time C > time B ) ≠  (A works at time C)

Fitzwilliam

Member

Registered: 2010-12-23

Posts: 21

Re: [SOLVED] I know my monitor supports 1080p72, but I can't convince Xorg

Thanks for the tip! The README wasn't incredibly useful in itself, but it showed me what terms I needed to search for. Cue some time with NVIDIA's online documentation, a few forums, and a good bit of trial and error, and I finally got it working. Here's my functional conf file, for the curious:

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync      28.0 - 33.0
    VertRefresh    43.0 - 72.0
    Option         "DPMS"
    ModeLine       "1920x1080_72" 160 1920 1950 1990 2035 1080 1083 1087 1092 +hsync +vsync
    Option         "Preferred Mode"     "1920x1080_72"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth   24
    Option         "ConnectedMonitor"   "DFP-1"
    SubSection     "Display"
        Depth       24
        Modes       "1920x1080_72"
    EndSubSection
EndSection

Note that the "ModeLine" part is unique to my monitor; you'll have to get your own. I'm also not sure that "ConnectedMonitor" is necessary, but I'm not messing with it at this point.

All I had to do after rebooting was go into KDE System Settings and manually change the refresh rate from 60.0 to 72.0. Works great!