QWXGA / 30 Hz with single-link DVI?

[Roland Scheidegger]

Andreas Schildbach wrote:
> Hi everyone,
> 
> I am struggling to find a dual-link DVI equipped notebook in order to 
> drive a QWXGA (2560 x 1600) monitor. The MacBook Pro seems to be the 
> only one available, but that's far too big and heavy. I'm more into the 
> sub-notebook size.
Typically, notebooks with discrete graphic chips nowadays should have
dual-link dvi outputs. Of course, sub-notebooks usually don't have
discrete graphic chips...

> 
> Recently I had one idea: What if I use single-link DVI, and only use a 
> video mode with half the bandwidth requirement than "normal"?
> 
> 2560 x 1600 x 24 @ 30 Hz should have a slightly lower bandwidth than 
> 1920 x 1200 x 24 @ 60 Hz (which just fits into single-link). The other 
> option would be to use only 12 bit color.
I don't think 12bit color modes are defined, but using a 30Hz mode is
sound in theory. This is pretty much how the IBM T221 (a 3840x2400
display) is driven.

> 
> Is any of the two approaches (or a combination) doable with current 
> (Intel?) graphics hardware? Is it supported by current Xorg?
It may be possible to convince (by adding a modeline) some of the
drivers to output such a mode, however I don't think your typical 30"
monitor accepts this. In particular, the first-gen 30" monitors (dell
3007wfp and similar) which didn't really have a video processor don't
accept anything except 2560x1600 at 60Hz or 1280x800 at 60Hz as far as I know.
But even current models might probably not accept it. Certainly such low
 vertical frequencies are never listed officially as supported.

Roland