my quick system specs are; Celeron G1620 2.7ghz, 4gb DDR3 1333mhz ram and Radeon 7750.
I don't know how much wattage my PSU has but it's a pretty cheap PSU, might be around 400watts. I was going to run 2 7750's crossfire. Should I change PSU'S? and if my PSU actually can't handle it what is the worst event that can happen in this scenario? Also does it have to be the same manufacturer like 1 amd 7750 from powercolor and the other Asus.
You will be stretched very thin with a 400w supply.(worst issue could be instability while playing games....most likely) I'd opt for a 550 to 600w psu.