I had this problem once in boinc where 1 card would not be detected by the program. I had to go into the bios and set "decode above 4g" to on (not auto) and they all worked after that.
It is a shot in the dark but it may be worth trying.
you do know that the asrock h81 pro btc r2.0 mobo doesn't have that option in the bios, please people do not mention things like this when ive already stated what mobo I'm using, if you don't know about the h81 pro btc r2.0 you have no reason to post here, I'm looking for certain people that have these gpus and a people having simular issue to what I'm dealing with
thank you:D