A 4850 requires a 6 pin external power source... Does your PSU have one?
You've been all over the internet, same question, and usually same answer. You really need a newer, better PSU. That Radius unit isn't even made any more. Full specs not available. No clue as to how old it is, but the P4 in the model name might be a clue. Hey, its your money, throw it away if you feel the need....