I seriously doubt u need a new PSU. I was running a 24pin mobo with a 20-pin PSU for a while. The 4-pin extra connector is standard the 8-pin power connector was reserved for server use, Id say that its backwards compatable and that the 4 extra connections are likely to just mirror the connections on the 4-pin. It wouldnt hurt to check your mobo manual and PSU manual to check that the 4-pin PSU cable matches the pin layout of the half of the 8-pin socket on mobo that u use.