I always recommend reading objective PSU test reviews on the EXACT PSU model you are interested in because as JackNaylorPE mentioned, there are good and not so good PSUs sold under many of the popular brand names and you have no way to know the PSU performance or quality without actually testing it properly.
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.
http://www.tomshardware.com/forum/314712-28-please-read-determine-power-required