The Coolermaster Elite 310 is a micro-atx case. Interior space is limited.
The Asus M4A785-M is a micro-atx motherboard with just one PCI Express 2.0 (x16) slot so a second video card cannot be installed.
Here is the official ATI recommendation for one ATI Radeon HD 5770 video card:
450 Watt or greater power supply with one 75W 6-pin PCI Express® power connector recommended.
The recommendation is for the entire pc system.
A good choice would be the Corsair VX450 available in the USA for $69.99. The final price after mail-in rebate is $59.99:http://www.newegg.com/Product/Product.aspx?Item=N82E16817139003