As the power numbers in this article show, none of these cards with no PCIe power connection needs a 400W PSU. GPU manufacturers overstate requirements in the attempt (sometimes futile) to account for the liar-labeled PSU-shaped objects out there that might only be good for half their labels (e.g. Logisys, Apevia, Diablotek, Sunbeam, other generic). Yes, a real 200W PSU may be needed, but not 400W. Even the HD7770 can run on a good 300W PSU using an adapter.