well my friend wanted to mod his xbox but he didnt know how he found a site that shows you how to add a usb port and he connect it to the 3 and 4 controller port wires and he never took the power supply out so now when the xbox turns on it blinks green 3x then turns orange
Nothing to do with power supply, you have a solder splash\bridge on the motherboard! Have a search around and try to find anything that doesn't look like a machine made it!
You can go to this: http://xbox-scene.com/articles/usb.php It talks about how to make a USB port for your Xbox, and maybe it can help you.