just to let you know 4 cards run fine on 4gb ram on windows 8.1 but 5-6 cards need 8gb...
at least for me;)
I've been running 5 290s on some of my rigs with 4GB ram with no real problems, so i'm not entirely sure that's true. It's got more to do with available virtual memory, i surmise.
Perhaps Claymore can comment on physical ram requirements, i would be curious to know.