Why stop at Quad SLI/Xfire? Why not 5 way or 6 way SLI/Xfire?

[White_Ice]

You're a wildman, do you know no boundries?

There are no boundaries for PC lol

 

[boxleitnerb]

Scaling is already terrible over 2 gpus

No it's not, see below.

Diminishing returns. Tri-Fire/3way SLI is only beginning to make sense. Quad makes no sense at all, beyond bragging rights.

If you have no clue about how to properly feed these cards, then yes. Otherwise, no. Think SGSSAA, ambient occlusion, 3D etc. And back it up with a powerful CPU (Ivy 4.5-5GHz). For example, friend of mine is CPU limited in Crysis 1 in 2560x1600 with 8xSGSSAA (he has 4xGTX680 and a 4GHz Nehalem).

4xSGSSAA can eat up to 50% performance
8xSGSSAA can eat up to 70% performance
Ambient occlusion can eat up to 60% performance
3D can eat up to 60% performance

There are enough scenarios where 3+ cards make absolutely sense and where scaling is good to excellent.

 

[BFG10K]

Is driver development that difficult?

Yes, it's tremendously hard, even just to get two cards working properly.

Also AFR adds one frame lag for every GPU beyond the first, so the lag from 6 GPUs would be horrendous.

 

[Rubycon]

What os for such a system? I was under the impression that Linux maxed out at 8 gpus.

CentOS

http://fastra2.ua.ac.be/