I would start by having just the basics connected....hard drive, ram, processor and video card, also make sure all your connections to the board are good. If you can boot that way, then start adding the other components one by one. Another thing to check is your led's. Are they all in the right place? If they arent, you wont be able to boot either. Also, how old is the monitor? Believe it or not, sometimes older monitors wont work with newer systems.