Do I need more Vcore if I changed from 3 x 6970s to 4 x 7970s.

My whole system is not stable anymore and I can't seem to stabilize it. No matter how much Vcore I put in. Its still give me the 0x9c BSOD and even if I try to raise VTT, same thing. Does the VCCSA has something to do with more PCIe cards?