After a few days of ENDLESS RESEARCH on the computer... I have FINALLY decided that I'm going to get a HD 6770. During those research hours, I check on the amd site and it said HD6770 min requirement for the psu is a 450watt. But on the XFX site, I said the gpu requires 500watt. I do NOT want to replace my PSU again because I recently bought this PSU. I will be playing games really demanding such as BF3,skyrim and Need for speed. Do you think I can run it perfectly fine on full load?
For a system using a single Radeon HD 6770 graphics card AMD specifies a minimum of a 450 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 25 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.
The Rosewill Stallion Series 450W (RD450-2-DB), with its maximum combined +12 Volt current rating of 28 Amps and with one 6-pin PCI Express supplementary power connector, is sufficient to power your system configuration with a single Radeon HD 6770.
Power supplies that only have a very short 1-Year warranty would worry me. Industry standard warranty period for reputable power supply brands is 3-Years. The OEM for the Rosewill Stallion Series 450W (RD450-2-DB), Solytech, is not known for making reliable power supplies which explains the very short warranty period. If that power supply blows up you'll know why.