|You need to consider the power consumption needs of the new board, not just the required connectors. It is doubtful your old ATX powersupply will be up to the task.|
What motherboard are you planning to use and what do you plan to run on it?
IE CPU, Ram, Drives, Graphics, etc
What are the amp ratings on each rail of your powersupply and what is the overall wattage rating?
You might want to read this:
Goin' Fishin' (Some day)