First off what is the minimum wattage of a PSU that a Radeon HD 4670 512MB gpu needs, if it is 400 will a Radeon R9 380 Gaming 2GB work on it?? I know a 300 wattage one will not, also is there a 20 dollar PSU that can run a Radeon R9 380 Gaming 2GB i want it to be on amazon by the way?? Also does this https://www.amazon.com/Apevia-ATX-XG450W-450W-Power-Supply/dp/B00YNXJMI6/ref=sr_1_3?s=electronics&ie=UTF8&qid=1465866444&sr=1-3&keywords=450+watt+power+supply have the hookups to run a Radeon R9 380??