I have a setup with two nvidia cards (Geforce GT 640 and GTX 980) set up as two different X screens. With the 410.78 driver it works fine, but with 415.25 I end up with a single X screen, the GTX 980 turns off (and I don’t see its outputs in xrandr either, but nvidia-settings shows both GPUs). I use the following minimalist xorg config
Section "ServerFlags"
Option "AutoAddGPU" "false"
EndSection
Section "ServerLayout"
Identifier "Layout"
Screen 0 "Screen0"
Screen 1 "Screen1" RightOf "Screen0"
EndSection
Section "Device"
Identifier "Card0"
BusID "PCI:2:0:0"
Driver "nvidia"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Option "Metamodes" "HDMI-0: nvidia-auto-select +0+0"
EndSection
Section "Device"
Identifier "Card1"
BusID "PCI:1:0:0"
Driver "nvidia"
EndSection
Section "Screen"
Identifier "Screen1"
Device "Card1"
Option "metamodes" "DVI-D-1: nvidia-auto-select +0+0"
EndSection
I tried to generate a config with nvidia-settings and two screens, but the result are the same, only the GT 640 works (PCI:1:0:0). However if I remove Screen0 from the config and only leave Screen1, then the GTX 980 works (so I can use either cards, but not at the same time).
I’ve run nvidia-bug-report.sh with both the old and new driver.
410.78: http://0x0.st/s58_.gz
415.25: http://0x0.st/s58L.gz