SDL on quad-head display

Hi everyone.

I’m developing an application which will have to use four monitors
(three as a single screen plus one for user interface). The setup will
use Xinerama extension to make a single big window about 3840x1024 in

Do you have any experience with writing to a surface that big? Can I
expect some unusual behavior?

I have tested Xinerama with SDL on dual head (Radeon X300 using
Xinerama, not MergedFB) and with a window spanning two monitors, a 48pt
size text scrolls quite nicely. The other graphic will be mostly static.

Do you know if I can use two dual head gfx cards for quad head
xinerama? Or should I buy a quad head unit (quite pricey, $800 for
Matrox G450 or QIP)? Or maybe use 2-head + 2 cards?

I will be using software surfaces along with Cairo and librsvg, so
drawing will be in-memory only. Which factors are the most important for
speed? The cpu-gpu bus (pci-x) and gpu-vram (256 vs 128 bit)?–
Maciej Grzywocz