your cpu is 65 watts
RAM 4 watts a stick
motherboard is 8 watts
hard drive is 10 watts to start up 5 watts read/write
and that 6670 is ~50 watts
so your talking about ~150 watts. i am not a big fan of online calculators because they do add in a little extra but you can check:http://www.extreme.outervision.com/PSUEngine
oh yeah a 500 watt is more than enough . . .