Need help with 6 cuda rig freezing up.

[GreenDust]

Hello everybody.
I recently built a 6 gpu rig (1070's). My specs are as follows :
Win 10x64
8gb ram, 16gb virtual ram
6x GTX 1070 cards
OC using MSI afterburner.

I am using Ethminer and Claymore. Both of them freeze up my computer to the unresponsive state within 5 minutes.
With 4 cards I didn't have that problem. Does it sounds like I need more ram or is there some settings in miners I need to tweak?