ATI Mobility Radeon HD 5400: How to fix resolution issue?

Question

Hi,
my laptop has a maximum screen resolution of 1366 x 768. I connected an external full hd monitor but I cannot set the resolution of 1920 x 1080.
I use gnome and the monitor setting utility of gnome give me the maximum resolution of 1600 x 900.
How fix this problem?
I use catalyst driver and this is my xorg.conf:
[tiziano@arch64 ~]$ cat /etc/X11/xorg.conf
Section "ServerLayout"
Identifier "X.org Configured"
Screen 0 "aticonfig-Screen[0]-0" 0 0
Screen "amdcccle-Screen[2]-1" RightOf "aticonfig-Screen[0]-0"
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Section "Files"
ModulePath "/usr/lib/xorg/modules"
FontPath "/usr/share/fonts/misc/"
FontPath "/usr/share/fonts/TTF/"
FontPath "/usr/share/fonts/OTF/"
FontPath "/usr/share/fonts/Type1/"
FontPath "/usr/share/fonts/100dpi/"
FontPath "/usr/share/fonts/75dpi/"
EndSection
Section "Module"
Load "record"
Load "dri2"
Load "dbe"
Load "extmod"
Load "glx"
Load "dri"
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
EndSection
Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "ZAxisMapping" "4 5 6 7"
EndSection
Section "Monitor"
#DisplaySize 340 190 # mm
Identifier "Monitor0"
VendorName "AUO"
ModelName "22ec"
EndSection
Section "Monitor"
Identifier "aticonfig-Monitor[0]-0"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
EndSection
Section "Monitor"
Identifier "0-LVDS"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
Option "TargetRefresh" "60"
Option "Position" "0 0"
Option "Rotate" "normal"
Option "Disable" "false"
Option "PreferredMode" "1366x768"
EndSection
Section "Monitor"
Identifier "0-CRT2"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
Option "PreferredMode" "1400x1050"
Option "TargetRefresh" "60"
Option "Position" "0 0"
Option "Rotate" "normal"
Option "Disable" "false"
EndSection
Section "Device"
### Available Driver options are:-
### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
### <string>: "String", <freq>: "<f> Hz/kHz/MHz",
### <percent>: "<f>%"
### [arg]: arg optional
#Option "NoAccel" # [<bool>]
#Option "SWcursor" # [<bool>]
#Option "Dac6Bit" # [<bool>]
#Option "Dac8Bit" # [<bool>]
#Option "BusType" # [<str>]
#Option "CPPIOMode" # [<bool>]
#Option "CPusecTimeout" # <i>
#Option "AGPMode" # <i>
#Option "AGPFastWrite" # [<bool>]
#Option "AGPSize" # <i>
#Option "GARTSize" # <i>
#Option "RingSize" # <i>
#Option "BufferSize" # <i>
#Option "EnableDepthMoves" # [<bool>]
#Option "EnablePageFlip" # [<bool>]
#Option "NoBackBuffer" # [<bool>]
#Option "DMAForXv" # [<bool>]
#Option "FBTexPercent" # <i>
#Option "DepthBits" # <i>
#Option "PCIAPERSize" # <i>
#Option "AccelDFS" # [<bool>]
#Option "IgnoreEDID" # [<bool>]
#Option "CustomEDID" # [<str>]
#Option "DisplayPriority" # [<str>]
#Option "PanelSize" # [<str>]
#Option "ForceMinDotClock" # <freq>
#Option "ColorTiling" # [<bool>]
#Option "VideoKey" # <i>
#Option "RageTheatreCrystal" # <i>
#Option "RageTheatreTunerPort" # <i>
#Option "RageTheatreCompositePort" # <i>
#Option "RageTheatreSVideoPort" # <i>
#Option "TunerType" # <i>
#Option "RageTheatreMicrocPath" # <str>
#Option "RageTheatreMicrocType" # <str>
#Option "ScalerWidth" # <i>
#Option "RenderAccel" # [<bool>]
#Option "SubPixelOrder" # [<str>]
#Option "ClockGating" # [<bool>]
#Option "VGAAccess" # [<bool>]
#Option "ReverseDDC" # [<bool>]
#Option "LVDSProbePLL" # [<bool>]
#Option "AccelMethod" # <str>
#Option "DRI" # [<bool>]
#Option "ConnectorTable" # <str>
#Option "DefaultConnectorTable" # [<bool>]
#Option "DefaultTMDSPLL" # [<bool>]
#Option "TVDACLoadDetect" # [<bool>]
#Option "ForceTVOut" # [<bool>]
#Option "TVStandard" # <str>
#Option "IgnoreLidStatus" # [<bool>]
#Option "DefaultTVDACAdj" # [<bool>]
#Option "Int10" # [<bool>]
#Option "EXAVSync" # [<bool>]
#Option "ATOMTVOut" # [<bool>]
#Option "R4xxATOM" # [<bool>]
#Option "ForceLowPowerMode" # [<bool>]
#Option "DynamicPM" # [<bool>]
#Option "NewPLL" # [<bool>]
#Option "ZaphodHeads" # <str>
Identifier "Card0"
Driver "radeon"
BusID "PCI:2:0:0"
EndSection
Section "Device"
Identifier "aticonfig-Device[0]-0"
Driver "fglrx"
Option "Monitor-LVDS" "0-LVDS"
BusID "PCI:2:0:0"
EndSection
Section "Device"
Identifier "amdcccle-Device[2]-1"
Driver "fglrx"
Option "Monitor-CRT2" "0-CRT2"
BusID "PCI:2:0:0"
Screen 1
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "aticonfig-Screen[0]-0"
Device "aticonfig-Device[0]-0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "amdcccle-Screen[2]-1"
Device "amdcccle-Device[2]-1"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection

Answer 1

Don't worry the native resolution of these cards are far higher than any consumer monitors out there, these GPU can comfortably drive a 30 inch dell with WQXGA resolution. And the resolution you can get on most consumers LCD screen is WUXGA, which could be used even with a laptop 5 years old.
Currently most of the cheaper LCD use a 16:9 rather than the 16:10, these are due to two factors mostly:
1) Cheaper to produce than 16:10 and this is one of the reason that the LCD have fallen in price, as production can squeeze the most amount of LCD panels out of each production ran, with minimal cutoff wastage.
2) Most of the widescreen movies are produced in these resolution (16:9), and many people use their LCD for movie watching and games (i do it a lot). 
The resolution of the graphics card can be changed, to fit either the 16:10 or 16:9 screens, so what you have to worry which one do you like.
The benefits of 16:9 are it is cheap, and there is plenty of supply from different companies, offer high resolution in small screen area, and good for movies and games. 
The benefits of 16:10 is that it got more vertical real estate, so there is less scrolling if you view a document. But they are more expensive, mostly reserved for higher end LCD, hard to find and probably not that much better than a 16:9 if you are getting a TN (most common and very cheap) LCD. 
For a cheap LCD stay away from Acer (low quality LCDs) and stay away from Samsung that allow you to rotate or raise the LCD (they break off really easily, i have 3 failures already), i personally like Benq and ASUS one because they offer the most bang for bucks in the 16:9 category, and many of them can be bought with HDMI input... TV, Xbox 360 and PS3.... 
Regards,
Jin Li
May this year, be the year of 'DO'!
I am a volunteer, and not a paid staff of Lenovo or Microsoft