I'm running Ubuntu 16.04 and I am using the proprietary NVidia driver (version 367.27). I have two graphics cards (a pair of EVGA Titan X) and two 4K displays (both are Dell P2715Q). The displays are connected to two DVI ports on the "first" Titan X (first meaning either PCI slot 1:0:0 or closest to the CPU, they're both the same in this case).
I noticed some graphical tearing and tracked it down to mismatched refresh rates. xrandr
shows that one display is using 30Hz and the other is using 60Hz.
When I attempt to configure through the NVidia X Server Settings application, I end up with a messed up X config (see below) - the second display doesn't get any image and apps are weird and stretched on the primary.
What steps can I take to get both monitors on the same refresh rate?
Will this require adding custom display and monitor sections, one for each monitor?
xorg.conf
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 367.18 (buildd@lgw01-52) Thu May 19 23:33:33 UTC 2016
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection
Section "Files"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "DELL P2715Q"
HorizSync 31.0 - 140.0
VertRefresh 29.0 - 75.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX TITAN X"
BusID "PCI:1:0:0"
EndSection
Section "Screen"
# Removed Option "metamodes" "DP-0: 3840x2160_60 +0+0, DP-2: 3840x2160_60 +3840+0"
# Removed Option "SLI" "On"
# Removed Option "metamodes" "DP-0: nvidia-auto-select +0+0, DP-2: nvidia-auto-select +3840+0"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "Stereo" "0"
Option "nvidiaXineramaInfoOrder" "DFP-2"
Option "metamodes" "nvidia-auto-select +0+0"
Option "SLI" "AUTO"
Option "MultiGPU" "Off"
Option "BaseMosaic" "off"
SubSection "Display"
Depth 24
EndSubSection
EndSection