The graphics card is a Club 3D Radeon HD 7870 Eyefinity 6 (that one: http://www.club-3d.com/index.php/produkte/leser.de/product/radeon-hd-7870-eyefinity-6.html) and I use 4 equal ~50" Philips FTV (I don't know the exact type, sorry).
I connected all over HDMI with these adapters: http://www.amazon.de/dp/B00D3N4RNC. I am able to use every display but only two at once.