I am about to put together a new (simple) PC. The MB is a Biostar 6200, the processor is an AMD Sempron 2800+. The MB has a socket, which the book says allows 12v to be connected to the processor (??????). A modern PSU has such a 4 pin connector, two black, two yellow wires i.e. 12 volts. I want to use an old PSU which doesn't have the 4 pin connector. Is it necessary?