Computer turns on but dosen't boot up!

Sorry im new at this but i have been building a computer. I have had it all put together and it worked fine. I went and got a new case, and hard drive for it. but ever since that i cant get it to work. I figured the power suppily went bad in it and replaced it with a 650w cheifmax . The computer will turn on and run but for some reason wont boot up? i have a Asus P7P55D Deluxe Motherboard with 6gb (3 different sticks) of DDR 3 Kingson ram with a Intel Dual Core I5 Processor! the Case is a Xclio Night hawk idk if thats really important to know but any advise will help!!

Thanks!!
 
Back