Should a 550w PSU work with an R9 280X + AMD FX 6300?

DasHotShot

Honorable
Better, is not defined by how many watts it outputs.

Getting a Seasonic, Enermax, EVGA or XFX gold/platinum certified PSU is BETTER than a cheaper, unreliable, uncertified brand/unit.

In terms of components, we don't know the rest of your system, however it is safe to say, 550 will almost certainly suffice on an average single gpu build.