yes just cpu but this 2 hd are not overclock and no issue, it's beta because i try 12.11 and 13.1 i have bad performance with firex. sorry for my bad english 
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windows 7 pro
core i7 3770k @4.0
16 go 1866mhz
2x sapphire hd7970 @1100mhz 2 x16 pci3.0
2x ssd
alim enermax 1000w 80G+
motherboard asus p8z77 ws