Re: Xinerama and GLX with dual GPUs, compatibility question
I'm running a tripple head setup for about a year using two 7800GTX
and three 1600x1200 LC displays. LCD1 and LCD2 connected to card1
operate in twinview mode. LCD3 connected to card2 is tied in with
Xinerama. LCD1 and LCD2 could also be defined as seperate screens.
Both varaints have pros and cons.
Concerning OpenGL: the window width/hight limit is currently 4096
pixels. If the window is bigger, then fallback to soft-rendering is done
(at least for me).
My first experimental setup used a 7800GTX for LCD1 and LCD2 and
a 6600 card for LCD3. I didn't have done any benchmarks at that time,
but i had the impression that replacing the 6600 with a second 7800GTX
didn't made a big difference for UT2K4: for this game, the CPU is
typically the bottleneck. Even if you can use a slower card for LCD3,
i would recomend buying the same card as used for LCD1+2, because
then you can also use an SLI setup in case you need it.
Concerning overhead because of xinerama: i once did some benchmarks
and IIRC, a 2560x1024 twinview setup using only the first card was
about 20% slower than a 3840x1024 using both cards with xinerama.