If it isn't, you can purchase most ASUS motherboards and they run either the atx power plug connector with the new P4 plug together, or you can if your Pc case doesn't have the new P4 plug, use a regular power connector, like what is plugged into you hard drives or cdroms along with the regular atx power supply connector.
You can use a P4 in an Antec SX 1030, 1035, 1040, 1080. I have 3 Antecs running ASUS P4S533 motherboards using Antec Sx1040 (2 each) and Antec Sx1080 (1 each).
No problems. Hope this helps. Just make sure your motherboard can hook up okay.
ROJAS