I've got a triple-head set-up running where 1 monitor is off
the internal Intel HD-4000 GPU and 2x monitors are off a GT550-Ti
using the nVidia drivers. I could not get xrandr support to work
(and attributed that to Intel / nVidia not co-operating). I found that
using the nVidia xserver setting GUI and hand-editing the xorg.conf
file to be the best solution. I have similar (but slightly) different
set-ups working under Fedora-17 and CentOS-6. All 3x screens are
in on large canvass (so screens can be drag from any monitor to any
where on the canvass, e.g., xinerama) across 2x X-servers -- so full
screen either occupies the 1x Dell 24" or the 2x E-Bay 27" "specials".
The key I found is locking things in with the BusID w/PCI designation
settings.
HTH
-rak-
Here is the xorg.conf -- in case that helps:
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 304.37 (mockbuild@) Tue Aug 14 06:30:17 CEST 2012
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" RightOf "Screen0"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "1"
EndSection
Section "Files"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "InputDevice"
# generated from data in "/etc/sysconfig/keyboard"
Identifier "Keyboard0"
Driver "keyboard"
Option "XkbLayout" "us"
Option "XkbModel" "pc105"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "FRT DIGITAL"
HorizSync 30.0 - 91.0
VertRefresh 56.0 - 61.0
Option "DPMS"
EndSection
Section "Monitor"
Identifier "Monitor1"
VendorName "Dell"
ModelName "Dell 2405FPW"
HorizSync 30.0 - 81.0
VertRefresh 56.0 - 76.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 550 Ti"
BusID "PCI:1:0:0"
EndSection
Section "Device"
Identifier "Device1"
Driver "intel"
VendorName "intel"
BoardName "intel"
BusID "PCI:0:2:0"
Option "monitor-HDMI2" "Monitor1"
EndSection
Section "Screen"
Identifier "Screen1"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "Stereo" "0"
Option "nvidiaXineramaInfoOrder" "DFP-0"
Option "metamodes" "DFP-0: 2560x1440 +0+0, DFP-2:
2560x1440 +2560+0; DFP-0: nvidia-auto-select +0+0, DFP-2:
nvidia-auto-select +2560+0"
# Option "metamodes" "DFP-0: 2560x1440 +0+0; DFP-0:
nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device1"
Monitor "Monitor1"
DefaultDepth 24
Option "metamodes" "HDMI1: 1920x1200 +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection