check that the new power supply your not trying to power the 4/8 pin connector with the 6 plus 2 pci video plug. most power supply have two 4 pin plugs that make up an 8 pin connector. also check on the back of the power supply to see that if there a red voltage switch on the power supply. sometime the switch not set right from shipping. if your in the us make sure it set to 110v.