Sometimes it works, sometimes not. Officially, the added 4 pins are supposed to support the PCI express graphics slot. I ran a TForce 6100 socket 754 mobo with a 20 pin PSU connector without incident. Of course, I was only using the integrated graphics at the time. Your best route is to try it and see. It should not harm the mobo or the PSU by trying. If it fails to boot or is unstable, you can buy a 20 to 24 pin adapter to take care of the issue. Note that an adapter potentially puts more current through a couple of the wires in the 20 pin PSU connector that could cause an overload in the wire, melting the insulation which could cause a fire or short out the PSU and/or other components. Careful consideration should be given to the amount of power your computer will likely consume through the appropriate voltage rails to determine if you would be at risk when using an adapter. If you have any doubts as to the safety of adapter usage, you should replace the PSU with one that has a proper 24 pin connecter.