my pc currently runs a sapphire hd 5770 perfectly fine, I notice on guru the specs tell me my psu needs to be at least 500 watts. Now my real question is, if I get a 560 ti will it run fine? (i dont have a 500 watt psu) If not would it be worth getting the gpu first for $100 and then a psu? or get a bfg 800 watt psu for $60 and get a gpu later down the line for more money. thanks in advance.