Wattage vise, 450W is enough for your build. But what i'm interested in is the make and model (or part number) of your PSU. Since not all PSUs are created equal and there are a ton of crap quality PSUs out there that fail to deliver the marketed total wattage and/or can't keep the voltage within ATX PSU standard of 5% on all rails (10% on -12V and -5V rails).