My recamend is fill all slots dont see capacity. see mhz in board and ram.Reason mhz is the key to achive speed. if board support 1600mhz u insert 1333mhz its waste because not get full speed of ram slot. if board support 1333mhz u insert 1600mhz its also waste of money (1333mhz ram is cheaper than 1600mhz)also u not utilise full speed of ram. (4x1600mhz=6400mhz =6.4ghz) vs (2x1600=3200mhz=3.2ghz). think.
Also my recamend is Buy "TRANSCEND" ram .reason other manufacturers give only 1year warenty but transcend give "lifetime warenty" so no need to warry about problems. Then cost "no more dealer and distributer " because anyone can "buy directly in TRANSCEND.COM" so cost lower then other.
Psu: coolermaster 750w 3years warenty.
u r cabinet is great.
buy 2gb x4 ram in 2000mhz u r board support upto 2000mhz or above. 2000x4=8000mhz =8.0ghz.all games not use more than 8gb ram.