welcome dude..try to put the 2 dimm in both red slot in the mobo, then like chino said check if all detected in bios.did you try the windows 8 or 7 OS first? or directly in OS 8.1? if not try if you like.
I know not long for now they will send out a new bios for fully compatibility on windows 8.1, but my point now is we must try first to confirmwhich has the problem the bios or the OS thats why try putting windows 8 or 7 for to be sure,if you can.
hey dude..@ what OS are now? are u in windows 8.1? well I know its odd but trying is not bad at all. try to run an OS windows 8 or 7maybe but not sure enough windows 8.1 is a new OS now so we can think that it might be little buggy OS for now..as you...
well for the psu issue in crossfire that wont be enough but for a single r9 290x and a watercooled set it will certainly can handle by ur psu now.but its up to you, take your time and just enjoy your overclock cpu for now...:o