I have 7 cards setup - works ok, but requires a monitor to boot. 5 cards setup on same MB - does not require monitor connected - not sure what this problem connected to (
Micax1, on the ASRock Z87 Killer (Fatal1ty), did you have to short any of the pins in the PCI-e slots to get all 7 GPUs to work/be recognized?
I'm running 2x rigs with 6x GPUs per on this same board. Works fine, but i can't get the 7th working or I get video errors when the Xorg tries to start. Possible driver issue (R9 290s and R9 280Xs)? Other than that the board is a champ, but yet it requires shorting of anything other than a 16x->16x riser, so that means USB risers require shorting in all ports. I'd avoid the first 1x as it seems to be the most problematic.