According to Maximum PC (July 2004, pg54), the extra connectors support increased power routing through both BTX and next-generation ATX motherboards that support the 75-watt PCI Express power requirement. The latest power supply apec also calls for the four-pin 12 V connector to run off of a separate 12 volt power rail. However, if you run a BTX (or ATX) board without a high-wattage graphic card, you can technically plug an old 20-pin main power connector into the new board without problem. But in the end, the article still advise to prepare to buy a new power supply to fully support PCI Express motherboards and the new graphic card.