I almost said something about OC but didn't because you didn't mention it...I thought that it would handle some OC but if you're getting shutdowns, then you need some more juice. Personally I'd swap out the cables instead of buying the X760...avoid any shipping/re-stock fees.
phenom II x 4 970be @ 4.0 ghz
2 x 4 gb ddr3 @ 1600
2 Evga 448 Classified Ultras; default is 810 mhz.
one card will o/c to 950mhz, with 1.150mv, and 2200 on the memory. voltage is maxed.
it will go to 960 or 970mhz, but thats it. 980 will crash.