Thermaltake TR2 430W

as long as your pwoer supply has a single 6 pin cpie power you can go with 7770. if your power supply doesn't have that cable your next choice should be the 7750 as it doesn't take additional power

The Thermaltake TR2 - 430W (W0070RUC) should have a combined +12 Volt continuous current rating of 27 Amps. It does have one 75 Watt 6-pin PCI Express power connector.

For a system using a reference clocked single Radeon HD 7850 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 24 Amps or greater and have at least one 6-pin PCI Express supplementary power connector.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important factor.

A reference clocked Radeon HD 7850 itself will only draw 8 Amps from the +12V rail during gaming and almost 8.5 Amps when running Furmark. That should be well within the Thermaltake TR2 - 430W (W0070RUC)'s capabilities.