Planning a dream rig for gpu mining, any recommendations and/or cheaper options (trying to be as budget friendly as possible):

1-2x mobo (7 pci-e):
http://www.ebay.com/itm/Asrock-970-Extreme4-ATX-Mainboard-Sockel-AM3-DDR3-USB-3-0-eSATA-/350765536098?pt=DE_Elektronik_Computer_Mainboards&hash=item51ab415362#shId

7* radeon 5850/6950

PSU:
Like 9999 or what ?!

CPU:
something stupid

RAM:
4gb/mobo: ram is like a dollar.

Do you people know how well could you mine with both 5850 and 6950 on the same rig and how well different versions of one graphic card will blend in?