[nutzer]

Nvidia cards cannot handle 1366x768.
You need to use 1360 or 1368 x 768 instead.

I don't know how it works with your cards, but I have an GTX8800 and a Philips 37'' LCD TV. (37PF5321). The TV has a native resolution of 1366x768. In the manual of the TV is only written that it supports (as PC modes) 800x600, 1024x768, 1280x768.

But knwo the clue.

In Windows XP and also Windows Vista I can drive it with 1366x768 in custom resolution mode and it definitely works!

in my xorg.conf I have

Section "Device"
    Identifier     "Videocard1"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 8800 GTX"
    BusID          "PCI:1:0:0"
    Screen          1
    Option         "UseEDID" "FALSE"
EndSection

and

Section "Screen"
    Identifier     "Screen1"
    Device         "Videocard1"
    Monitor        "TVLCD"
    DefaultDepth    24
    Option         "TwinView" "0"
    Option         "UseEDID" "FALSE"
 #   Option         "metamodes" "DFP-1: 1366x768 +0+0"
    Subsection "Display"
      Depth         24
      Modes        "1920x1080" "1366x768" "800x600"
    EndSubSection
EndSection

and it only uses the 800x600 resolution.

but in the Xorg.0.log log he is just discarding the HD modes :

(II) NVIDIA(1): Assigned Display Device: DFP-0
(WW) NVIDIA(1): No valid modes for "1920x1080"; removing.
(WW) NVIDIA(1): No valid modes for "1366x768"; removing.
(II) NVIDIA(1): Validated modes:
(II) NVIDIA(1):     "800x600"

so whats the problem?

Cause its working in windows I cannot imagine thats impossible in Linux!