1050ti vs rx570

I can't decide if i should buy gtx 1050ti or rx570. GTX 1050ti is asus strix oc version and RX570 is Expedition 4gb. I want to get 1050ti because i don't have a good psu with 8pin just 6pin so that's the reasone i want to get 1050ti. I don't have a good cpu so i don't think a would get anything...