Setting-up a new video card or monitor is still the worst side of linux, both for beginners but also for advanced users. It is very easy to set the most common monitors in most linux systems but I have lost several hours every time I have tried to use large o special monitors.

Here I post my current working xorg.conf files that may solve most problems for users of 1080p monitors. They worked for me with old ati cards (ati rage 128 pro) and old nvidia (nvidia quadro NVS280 dual) both with nouveau free driver and nvidia propietary driver.

# Experts only: Copy and paste the modeline lines and add the video modes and maybe your are done for a single monitor installations for 1920x1080 1080p tft lcd monitors.

#

The ATI single monitor xorg.conf can be applied to any configuration just editting the driver name (in red). 

Remember to change the keyboard layout and language/country (in blue in my setup: es is for Spanish (es, es_ES, or ca_ES for catalan language).  Fix following your needs.

Single monitor - xorg.conf for Ati Rage 128 pro (r128) and 1080p monitor (acer 23'' 1920x1080, db15 connector) Working. Solved.

1.- make a copy of your xorg.file  (it may save you ...)

     cp  /etc/X11/xorg.conf /etc/X11/xorg.conf.my

2.- Edit/Save as /etc/X11/xorg.conf the following block of text

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by a configurator and manually edited.
#
# Edit this file with caution, and see the /etc/X11/xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command from runlevel 3:
# videoconfig

# Files ( File pathnames )
#_______________________________________________________________________


# ServerFlags ( Server flags )
#_______________________________________________________________________

Section "ServerFlags"
# Option "NoTrapSignals"
# Option "DontVTSwitch"
Option "DontZap" "off"
# Option "DontZoom"
# Option "DisableVidModeExtension"
# Option "AllowNonLocalXvidtune"
# Option "DisableModInDev"
# Option "AllowNonLocalModInDev"
# Option "blank time" "10" # 10 minutes
Option "standby time" "10"
# Option "suspend time" "30"
# Option "off time" "60"
# Option "EstimateSizesAggresively" "0"
Option "AutoEnableDevices" "false"
Option "AutoAddDevices" "false"
Option "AllowEmptyInput" "false"
EndSection


# **********************************************************************
# Module section ( Dynamically loadable modules )
#_______________________________________________________________________


# Extensions ( Extension enabling )
#_______________________________________________________________________

Section "Extensions"
Option "Composite" "enable"
EndSection


# InputDevice ( Input device description )
#_______________________________________________________________________

Section "InputDevice"
Identifier "Keyboard1"
Driver "kbd"
# Option "Protocol" "Xqueue"
# Option "AutoRepeat" "500 5"
# Option "Xleds" "1 2 3"
# Option "XkbDisable"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "es"
# Option "XkbVariant" "us"
Option "XkbOptions" "terminate:ctrl_alt_bksp"
EndSection

Section "InputDevice"

# Identifier and driver
Identifier "Mouse1"
Driver "mouse"
Option "Protocol" "Auto"
Option "Device" "/dev/input/mice"
# Option "Protocol" "Xqueue"
# Option "BaudRate" "9600"
# Option "SampleRate" "150"
# Option "Emulate3Buttons"
# Option "Emulate3Timeout" "50"
# Option "ChordMiddle"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
Identifier "Pad1"
Driver "synaptics"
Option "Protocol" "auto-dev"
Option "Device" "/dev/tp1"
Option "TapButton1" "1"
# Option "VertEdgeScroll" "1"
# Option "HorizEdgeScroll" "1"
# Option "LeftEdge" "1700"
# Option "RightEdge" "5300"
# Option "TopEdge" "1700"
# Option "BottomEdge" "4200"
# Option "FingerLow" "25"
# Option "FingerHigh" "30"
# Option "MaxTapTime" "180"
# Option "MaxTapMove" "220"
# Option "VertScrollDelta" "100"
# Option "MinSpeed" "0.09"
# Option "MaxSpeed" "0.18"
# Option "AccelFactor" "0.0015"
Option "SHMConfig" "on"
EndSection


# Device ( Graphics device description )
#_______________________________________________________________________

# Any number of graphic devices sections may be present

Section "Device"
Identifier "Videocard1"
# VendorName "Unknown Vendor"
# BoardName ""
Driver "r128"
# BusID ""
# Option "RenderAccel" "true"
# Option "XaaNoOffscreenPixmaps" "on"
EndSection


# Monitor ( Monitor description )
#_______________________________________________________________________

Section "Monitor"
Identifier "Dell1905"
Option "DPMS"
HorizSync 30-65
VertRefresh 30-60
EndSection


Section "Monitor"
Identifier "LG1080p"
#
HorizSync 31.5 - 80.0
VertRefresh 60
DisplaySize 510 287
# Option "UseEdidFreqs" "1"
# Option "DPMS"
# Option "ReducedBlanking"
# Modeline "1920x1080_60.00" 172.80 1920 2040 2248 2576 1080 1081 1084 1118 -HSync +Vsync
ModeLine "1080p" 148.50 1920 2012 2068 2200 1080 1082 1088 1125
# ModeLine "1080i" 74.52 1920 1952 2016 2208 1080 1084 1096 1126 interlace
# ModeLine "720p" 73.825 1280 1320 1368 1640 720 722 724 751

Option "ReducedBlanking" "TRUE"
Option "ExactModeTimingsDVI" "TRUE"
Option "ModeValidation" "NoDFPNativeResolutionCheck"
EndSection

# Screen ( Screen configuration )
#_______________________________________________________________________

Section "Screen"
 Identifier "Screen0"
Device "Videocard1"
Monitor "LG1080p"
# Monitor "Dell1905"

DefaultDepth 24

Subsection "Display"
Depth 8
Modes "1080p" "1920x1080_60.00" "1440x900" "1280x1024" "1024x768" "800x600"
EndSubsection
Subsection "Display"
Depth 16
Modes "1080p" "1920x1080_60.00" "1440x900" "1280x1024" "1024x768" "800x600"
EndSubsection
Subsection "Display"
Depth 24
Modes "1080p" "1920x1080_60.00" "1440x900" "1280x1024" "1024x768" "800x600"
EndSubsection
# Subsection "Display"
# Depth 32
# Modes "1920x1080_60.00" "1440x900" "1280x1024" "1024x768" "800x600"
# Modes "2560x1600" "2048x1536" "1920x1440" "1920x1200" "1920x1080" "1680x1050" "1600x1200" "1600x1024" "1440x900" "1400x1050" "1400x900" "1360x768" "1280x1024" "1280x960" "1280x854" "1280x800" "1280x720" "1200x900" "1152x864" "1152x768" "1024x768" "1024x600" "854x480" "848x480" "800x600"
# EndSubsection
EndSection


# ServerLayout ( Overall layout )
#_______________________________________________________________________

Section "ServerLayout"
Identifier "Simple Layout"
 Screen "Screen0"
InputDevice "Mouse1" "CorePointer"
InputDevice "Pad1" "SendCoreEvents"
InputDevice "Keyboard1" "CoreKeyboard"
EndSection


# DRI ( DRI-specific configuration )
#_______________________________________________________________________

Section "dri"
# Access to OpenGL ICD is allowed for all users:
Mode 0666
# Access to OpenGL ICD is restricted to a specific user group:
# Group 100 # users
EndSection

# end of /etc/X11/xorg.conf (xorg X Window System server configuration file) #

3.- Type [Ctrl]+[Alt]+[<- backspace] to restart your X11 graphics subsystem

4.- I hope you are done !

Working system 

Dell GX-260 SFF (P4-2.66GHz, 2GB RAM) Linux Mint 12.0 + Nvidia Quadro NVS 280 AGP

Dell GX-260 SFF (P4-2.66GHz, 2GB RAM) Linux Mint 12.0 + Nvidia Quadro4 550 XGL AGP

One Acer 1080p 23'' TFT monitors