I just put together a system using Abit KN9 sli board which i soon found out had a 24 pin
connector. Checked the mobo manual and it said I could use the 20 pin connector without any adaptor or anything but recomended having at least a 350 watt psu to avoid system instability.
Its worked so far, but all I did was install windows and some drivers. Since the 20 Pin connector is smaller then the 24 obviously, the clips do not line up meaning that the cord is not very secure on the motherboard but that shouldnt be much of a problem.
Also this is the first time Ive tried this so I dont know if it works for all mobos and psu's.