VGA/HDMI EDID

[ToadProphet]

Hi all,
I'm trying to attach a Samsung LCD (LN-S3252D). I'm using a NV 6200 connected with a DVI->HDMI cable. However, it seems I'm getting different EDID modes from the HDMI port than I am on the VGA port. Several modes are missing from HDMI... one in particular that I'd like to use is 1360x768. Pardon me if this is a dumb question, but is this normal?
Using 9746 I've tried to force the mode using:

Option         "UseEDID" "FALSE"
Option         "ModeValidation" "NoDFPNativeResolutionCheck, NoMaxSizeCheck"

in the xorg.conf with no luck. Log reports:

(WW) NVIDIA(0): Unable to use mode "1360x768" for DFP-0; cannot compute
(WW) NVIDIA(0):     backend DFP timings (mode is larger than native backend
(WW) NVIDIA(0):     640 x 480).

I'm probably missing something very simple... any ideas? Thanks