Could be PSU.  I hear those Toxics can be power hungry.  I have 2 MSI 7970 Twin Frozr and a MSI 280X GAMING on a 1050AX Corsair that is no problem though.  What is the brand of PSU?  Rating? 

Also, try undervolting a bit and then dropping the core clock down maybe to 1050 each.  I run all mine at 1040, anything over that I get less hashrate.