since i dont know what the psu is, its probably the quality of the psu and not the wattage. computers in general can drain a small amount of power, its the quality of the psu that decides how much real power it can draw from the wall and produce into dc current.
yes it needed 2 6 pin. I had to use a converter for one though. 2 molex to a six pin. I have to assume there's something wrong with the power supply cords or something. just not sure atm. hard to tell..