For a system
using a single Radeon HD 7970 GHz Edition
graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a 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!!! Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.
You may find power supplies on the market that supply more than enough Wattage to run the system. However, many of them lack the Amperage capacity on the critical +12 Volt rail, which is necessary to properly power the critical components in the system (i.e. CPU and GPUs). This is the reason why graphics card manufacturers overstate the power supply wattage, usually by at least 50 Watts, to take into account those power supplies that have the weaker +12 Volt rail(s).
The OCZ ModXStream Pro Series 700 Watt (OCZ700MXSP)
, with its combined +12 Volt continuous current rating of 46 Amps
and with one 6-pin and one (6+2)-pin PCI Express supplementary power connectors
, is sufficient
to power your system configuration with a single Radeon HD 7970 GHz Edition
. This power supply is a poor choice because it is unable to deliver 700 Watts.
You'd be better off getting this XFX 650W PRO650W Core Edition Single Rail ATX 12V 53A 24PIN ATX Power Supply 80PLUS Bronze PSU that uses Seasonic as its OEM.http://www.ncix.com/products/?sku=59616&vpn=P1650SNLB9&manufacture=XFX