Hello I just ordered new amd XFX RX-470P436BM for my Dell Optiplex 9020 Mini-Tower PC. (http://www.newegg.com/Product/Product.aspx?Item=N82E16814150776&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-Veeralava LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=6202798&SID= ) Can anyone tell me what's the power supply requirement? and which PSU to buy?