hello simon,
thanks for your reply and tipps!

i´m already on production,
it´s not possible to change the macs...
so i have to deal with this, in the end each cat has to play 1 file,
around 3k by 1080...

would also a GTX670 for PC work, or only the 680?

also,
how do you normally deal with output resolutions?
we didn´t get it to work to connect a mac directly to a christie roadster 18K HD, only change is to use an imagepro ( in this case 6 ).
no matter if i use 2 outputs of the matrox or directly to outputs from the grahpiccard.

when i test, i used a screenproHD to programm an edid of 1920x1080/p60 on geven dvi detective, in the testsetup everything went fine ( going from the mac to TH2G, then DVI Detective, then DVI Splitter, 1 out to Panasonic Beamer, 1 out to TFT),
but with the christies it was impossible...
it doesn´t matter if it was the mac with quadro 4000 or the one´s with ati 5770, everywhere the same problem.
so we get 6 imagepros tomorrow, then it works ( imagepro says signal from mac 59.94 or so instead of 60, but the christie won´t accept this)
OR does it make a difference when i start catalyst,
i recognice the screen changes when starting the programm
does catalyst do a better resolution managment then mac os,
or does it depend from mac os?

thx, all the best, roman