[Openchrome-users] strange startup, and can't run 1920x1080, SP8000E w/DVI-02

[gpeters@deepsky.com]

Folks,

I've been reading what I can and trying to get my display working.  I
have downloaded and compiled the latest svn 288, and now have my
SP8000E working over DVI at 1280x1024[1].  

I'd like to get 1920x1080 working.  I try this modeline

        Modeline        "1920x1080"   148.50   1920 2004 2048 2200   1080 1084 1089 1133

and I get this in my log around it:

(II) VIA(0): ViaValidMode: Validating 1920x1080 (148500)
(II) VIA(0): ViaModePrimaryVGAValid
(II) VIA(0): Required bandwidth is not available. (497664000 > 461000000)
(II) VIA(0): Not using mode "1920x1080" (mode clock too high)

and so begins my puzzlement.  Reading the source, the suggestion is that
this is a memory bandwidth issue; does this mean that my system is just
too slow?  Unfortunately, my monitor doesn't support refresh rates below 58Hz,
so without interlacing, I don't have a good way to reduce my memory bandwidth....

I've tried depth 16, this works.  But -depth 24 -fbbpp 24 does not work.

Any suggestions?  What part of my hardware is limiting me here?

--
[1] However, once I start X, I can't ever go back to text mode, and I
must start and exit an X server with VBEModes before it shows up.
I've put this gymnastics in my rc.local, but I'd sure like to figure
out why I need it.