So I finally found enough time at $work to set up my triple monitor desktop. I received an new desktop and monitor a few months ago; I was already running dual monitors and the new system came with a monitor.
I am running Fedora16 on my desktop with Xfce desktop environment. The new system is a Dell Optiplex 980 with an ATI Radeon 3450HD. I added the ATI Radeon X600 (PCIE) card out of the old system, a Dell Optiplex GX620. Both cards have the capability to run dual monitors so I currently have the capability to run four screens. Configuration is posted below the fold.
Since RandR 1.3 showed up without support for multiple card support I am still using Xinerama. I created three configuration files in /etc/X11/xorg.conf.d: 80-triple-devices.conf, 80-triplescreens.conf, and 80-triple-monitors.conf.
Caveats of this setup are the GDM login has a single display mirrored across three monitors. Also once I login I have a primary monitor, a secondary monitor, and a mirror of the secondary monitor until I run the following command:
/usr/bin/xrandr --output DVI-3 --right-of DVI-2
80-triple-devices.conf: Section "Device" Identifier "Card0" Driver "radeon" BoardName "Radeon X600 (PCIE)" VendorName "ATI" BusID "PCI:2:0:0" Screen 0 EndSection Section "Device" Identifier "Card1" Driver "radeon" BoardName "Radeon HD 3450" VendorName "ATI" BusID "PCI:1:0:0" Screen 1 EndSection 80-triple-screens.conf: Section "Screen" Identifier "Screen0" Device "Card1" Monitor "Monitor0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 modes "1600x1200" EndSubSection EndSection Section "Screen" Identifier "Screen1" Device "Card1" Monitor "Monitor1" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 modes "1600x1200" EndSubSection EndSection Section "Screen" Identifier "Screen2" Device "Card0" Monitor "Monitor2" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 modes "1680x1050" EndSubSection EndSection 80-triple-monitors.conf: Section "ServerLayout" Identifier "Layout All" Screen 0 "Screen0" 0 0 Screen 1 "Screen1" RightOf "Screen0" Screen 2 "Screen2" LeftOf "Screen0" Option Xinerama EndSection Section "Modes" Identifier "Modes0" ModeLine "1680x1050" 146.00 1680 1784 1960 2240 1050 1053 1059 1089 +hsync -vsync EndSection Section "Modes" Identifier "Modes1" Modeline "1600x1200" 161.00 1600 1712 1880 2160 1200 1203 1207 1245 -hsync +vsync EndSection Section "Monitor" Identifier "Monitor0" VendorName "Dell" ModelName "2007FP" UseModes "Modes1" HorizSync 30-83 VertRefresh 56-76 Option "DPMS" EndSection Section "Monitor" Identifier "Monitor1" VendorName "Dell" ModelName "2007FP" UseModes "Modes1" HorizSync 30-83 VertRefresh 56-76 Option "DPMS" EndSection Section "Monitor" Identifier "Monitor2" VendorName "Dell" ModelName "P2210" UseModes "Modes0" HorizSync 30-83 VertRefresh 56-76 Option "DPMS" EndSection