A few don't come with a power cord, but you can re-use your old one. I don't know of any proprietary connections on your motherboard that require a special ps. If in doubt, register and post your question on the hp website in a forum section. Also be sure the toggle switch on the back is in the (-) position when you hit the power button. Finally, you may try resetting the motherboard bios by removing the board battery for one minute with the power supply unplugged, then replace. You may have to use an "f" key when you first see a post screen; just use f10 to save and exit, or you can check the boot order first.