Ok so i have 2 graphics cards, one that clocks at 600watts and the other is 300watts. Do i need to get a 1000watt power supply to have them both work to increase gaming performance?
No you don't need a 1000 Watt PSU.
The numbers you have quoted are probably manufacturers recommended specs and are over stated . The GTX 550 needs a single power cable and the other card does not need one at all.
So i would say any decent PSU with a PCIE cable or two rated at around 34Amps should be good enough. I would look at something around 600 watts.
If you want to objectively, accurately and scientifically determine what PSU power is required for your Vid card and PC in both watts and 12v rail amps., the forum Utility link below will show you how easy it is to calculate this information and objectively determine which PSUs are quality built, reliable PSUs that can meet your needs. Be advised that the available 12v rail amps. is just as important as the total PSU wattage. You need both to be correct.