HP LP3065 Monitor not displaying in 2560x1600 on Ubuntu 9.04 with ATI Radeon HD 2400 XT

Question

I just got a new HP LP3065 30" monitor. It is supposed to support a 2560x1600 resolution. However, the biggest I am getting is 1280x800. I just got a new graphics card ATI Radeon HD 2400 XT and installed the ATI Catalyst™ 9.8 Proprietary Linux x86 Display Driver on my HP Compaq dc7800 PC running Ubuntu 9.04.

My xorg.conf is attached. I added the Modelines line as well as the Modes line in the subsection "display" to try to remedy this issue.

### xorg.conf ###
Section "ServerLayout"
 Identifier     "aticonfig Layout"
 Screen      0  "aticonfig-Screen[0]-0" 0 0
EndSection

Section "Files"
EndSection

Section "Module"
EndSection

Section "ServerFlags"
 Option     "Xinerama" "off"
EndSection

Section "Monitor"
 Identifier   "Configured Monitor"
EndSection

Section "Monitor"
 Identifier   "aticonfig-Monitor[0]-0"
 DisplaySize  641 400
 HorizSync    100.0 - 100.0
 VertRefresh  60.0 - 60.0
 ModeLine     "2560x1600" 268.0 2560 2608 2640 2720 1600 1603 1609 1646 +hsync -vsync
 Option     "VendorName" "HP"
 Option     "ModelName" "LP3065"
 Option     "DPMS" "true"
EndSection

Section "Device"
 Identifier  "Configured Video Device"
EndSection

Section "Device"
 Identifier  "aticonfig-Device[0]-0"
 Driver      "fglrx"
 BusID       "PCI:1:0:0"
EndSection

Section "Screen"
 Identifier "Default Screen"
 Device     "Configured Video Device"
 Monitor    "Configured Monitor"
EndSection

Section "Screen"
 Identifier "aticonfig-Screen[0]-0"
 Device     "aticonfig-Device[0]-0"
 Monitor    "aticonfig-Monitor[0]-0"
 DefaultDepth     24
 SubSection "Display"
  Viewport   0 0
  Depth     24
  Modes  "2560x1600" "1920x1200"
 EndSubSection
EndSection

Answer 1

Are you sure you have a dual link cable?

The specs say: Supports Single-Link DVI for 1280x800 with HDCP

Answer 2

According to some online resources the ATI Radeon HD 2400 XT comes in either a Dual-VGA or Dual-DVI. The answer is we got the wrong one. :(

Make sure if you are trying to push to a 30" you have dual-link DVI. Oops. Sorry.