Switch the motherboard to something with better cooling on the caps, your overclocks will be quite limited on that board ~4.4Ghz at the most.
Not sure which of the following is the best overclocker but browse around a bit.
Asrock Z68 Extreme 4 Gen 3 if you want to stay with asrock.
Asus P8Z68-V (or Pro) Gen3
MSI Z68A-GD65 Gen3
But yeah with 2x7950 you will want to have a mobo that supports PCIe Gen3.