For a
system using a
single Radeon R9 280X graphics card AMD specifies a minimum of a 600 Watt or greater
system power supply. The power supply should also have
a maximum combined +12 Volt continuous current rating of 42 Amps or greater and have at least
one 6-pin and one 8-pin PCI Express supplementary power connectors.
Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.
Overclocking of the CPU and/or GPU(s) may require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.
The
Super Flower Golden Green Pro 550W (SF-550P14XE) power supply unit, with its
maximum combined +12 Volt continuous current rating of 45 Amps and with
two 6-pin and two (6+2)-pin PCI Express supplementary power connectors, is
sufficient to power your system configuration
with a single Radeon R9 280X graphics card.
It's essentially the same platform that is used for the Rosewill Capstone-550.
http://www.rosewill.com/products/1804/productDetail.htm
http://www.newegg.com/Product/Product.aspx?Item=N82E16817182068