Thank you! I have 400W PSU, and i think it will works fine. I have calculated a power consumption of my all components (including HD7770) and result is a 309W (260w but recomended wattage is 309).
My configuration is: Core 2 Quad Q8300, 4x1GB ram, 250GB 7200rpm HDD. And i have plan to overclock my CPU to 2.80-90 GHz.
Thank you for answer!