I recently had a 400 watt power supply die on me so when replacing it I moved up to a 500 watt. Upon connecting the power supply for some reason I can get everything from my motherboard and Processor to my Video card and 2x 120mm case fans to run but any time i connect my hard drive everything fails to turn on. I believe it is a power issue but with the increase in power from my original Power Supply to the new one i cannot understadn what would be going wrong. Is there a specific way required in connecting a Sata hard drive that i have overlooked or could it possibly be a bad hard drive causing the problem?

are you connecting it using the sata-type power connector or the ide-type one? never use both at once

To determine if the hard disk is really the problem, you stated that the system fails every time you connect the power supply of the hard drive, this means that you need to try connecting a different hard disk, if it works, well it seems that the power part of the hard drive causes the problem.

This happens to me but on a CD-ROM drive, I thank God for that... Good luck.