Wiring up GPU's to RM1000X help

[Tocmin0418]

Recently purchased 2 RM1000x PSU's for my mining rig, i had 4 gpus plugged in running fine. Plugged the 5th on in and poof (spark and smoke) psu dead. Wattage at the wall was 675 on the 4 gpu's. Miners were reading 150ish a card and 70 for the mobo, cpu, sata makes sense. Now im not an electronics expert but from the info ive been able to look up i should be able to plug any of these 8 pin connects into any of the 8 pin slots correct? 1 x 8 pin to 4/4 for the cpu, and 5 x 8 pin to 2 x 6/2 connectors (1 split to the riser and the other split to the gpu). Am i missing something? ive seen some info regarding mismatching rails and thought id come here to ask the question before i blow another PSU up. Any help would be appreciated, are the picture of the cables and back of the psu