Recently bought a new tower for my older computer and in turn had to buy a new PSU because the old one was too big for the new case. My new power supply won't turn on the new mother board. The old one still works so i know its not the Mobo, and the new one works cause i tried it on another computer. My mobo only has a 20 pin connector and the new PSU has a 20+4 connector but i just didn't plug in the other 4. Is there a different PSU i need to get or is something else up?