I just bought a WD 320 Gb SATA hd. My motherboard has 2 sata ports built in. I have a molex power adapter for SATA. I mount the HDD and try to power on my machine. My led's flash for a sec, then all power goes out. I have to reset the power switch on the rear of machine. I currently run 2 ide HDD and am replacing with the SATA. Can't power on system with SATA HDD power to drive connected. No problems with IDE. Was told probably on board SATA connectors so I purchased a PCI card. No change in problems.