Just I bought Sapphire HD7770 Ghz Edition. Manufacturer suggest 450watt psu but I have 400watt psu. I set my graphic card to pc. I can run pc well. I tested play games. Just Cause 2, Skyrim vsvs. I dont have any problems for now but I am afraid of encounter problems so I need help.
Your psu is just fine. HD 7770 can run on 350 watts psu. If you are worried about your psu try to get a quality psu brand like seasonic, corsair or antec. Don't get me wrong here.. your psu is okay unless you add more stuff on your pc or oc.
You're good. Your whole system draws less than 200w at full load.