My 400w corsair powers my whole rig with out any problem. I don't know about a no name 450w though. Seems a little iffy to me how many amps does it have on the rails? My corsair has 30amps on 1 12v rail which is plenty to power the rig in my sig. I would probably go for it it should get by just barely. Although if it's going to be a gaming machine I would get a new PSU as soon as possible.
Also to answer you're question it use 1 6pin PCIe connector to power.