650watt is not enough for dual video cards. You should buy at least, I would say, 750watt, 850watt is recommended. You'll need to buy a psu with 3x6pin and 1x8pin PCI-E connectors. R9 290=6+8pin R9 270x DC2T=6+6pin
you will need to upgrade your psu
also i don't understand why you are adding 2 different cards.
When a gpu says that it needs (W++) that is for the whole system. With the "titan killer" it is pretty demandive, get a 800+ psu