On the X8SAX are 3 power connectors, 24pin, 8pin and 4pin. Is it mandatory to connect the 4pin?
When you want to be sure every configuration works, we advise to use all 3 powerconnectors on the mainboard. It depends on the video card that will be used. It can be that it needs extra power from the PCIe slot, that is delivered by the 4pin power connector.