AMD V7900 and 2k EDID question

Hi

a colleague stumbled upon this problem: he uses an older AI server, Animal rack, with a V7900 card. This goes directly to two projectors (connected via DVI and DVI/DP adaptors). He uses Christie L2K1500, which have a native resolution of 2048x1080.
Problem: as soon as he connects two projectors, he cannot change the frame rate or any other setting any more. And he cannot activate any of the two more outputs. Windows/the graphic card just allows these two projectors. However, everything is fine with just FullHD displays - I could connect and run 4 displays out of the box, when I got his machine back.
Furthermore, he encountered problems with video input (Datapath HDSDI): it did not run smoothly.

My problem: I cannot get hold of such projectors - for an affordable price just for testing. Hence my questions:
- has anyone already encountered such problems?
- if yes: is there a workaround?
- is it possible that the 2k EDID tells the graphic card to misbehave in such a way?
- is it possible that this also influences the video input?

Thanks in advance for any idea you might share.

Sebastian