I'm not sure I agree that 3x30" will be playable - at least with high settings. Check out my benchmarks (link to the left). A GTX295 still struggles in many instances at 5.3MP (3x1680x1050). Hopefully I can get a 2GB GTX285 SLI rig to test soon. I've already seen where the 1792MB version of the GTX275 outperformed the 896MB in 3x1680x1050. I'm guess at 3x2560x1600 you'd need almost 4GB of RAM per card.
Of all games I tested (including crysis), the only game I´ve seen at 7680x1600 using more than 1GB vram was GTA and FC2 (and this only by a few MB). Of course without AA. Crysis was bellow 1GB too (in High, vhigh not tested), althought only by a few MB.
It´s easy to test with a vram monitoring utility. Before a buyed my 285gtx 1GB, I was between 1GB and 2GB versiones. After testing was done, I decided for the 1GB version. vram doesn´t scale at the same rate as resolution.
Most games don´t use more than 800MB at 7680x1600. And BS, properly configured, even allows for 4xAA at 7680x1600 for a very nice 40-50fps in win7. And that is with SoftTh, not a native driver solution from the graphic card producer and designer.
My rig is a 3x30". Trine, EVE Online and Dead Space are playable with all settings to max. Trine is barely playable, at 25-35fps (but playable), Dead Space is a something better, with 30-40fps (playable, but play it at 5040x1050 @ th2go instead softth), and EVE online is not fully tested (done at request with a demo), but probably can do 50-60 with all to max and some AA if SoftTh is properly configured.
http://www.widescreengamingforum.com/node/10551
http://www.widescreengamingforum.com/node/
And thats with a 285gtx (pcie2.0) + 8800u, with 8800u limiting at some degree pcie bandwidth (motherboard and 285gtx are pcie2.0), as softth is very pcie bandwidth dependant at that resolution.
My point is: if I can just play now some (very few) games at 3x30" at max detail / no AA, with only one gpu working and with a third party freeware utility using hacked directx libraries. If I put four, more powerful gpus (quad CF / quad SLI if nvidia reacts) with native driver suport for multimonitor, things can only go better.
Because one of the big limitations for softth is wich doesn´t support multigpu, so if multigpu multimonitor support is open for resolutions above 5040x1050, I´m pretty sure many games can be played at 12mp. Not very demanding games, but many port games will do and some pc native games too.
So I´m
really waiting for an alternative to SoftTh to improve my frames at 76x16. Anyway, BS is where I need more to play at native res, and (after many many testing) I can play quite good at native resolution + 4xAA and all max except for one secondary graphic setting.