Computer building issue
 

edit: the computer fans and all that start running now, but nothing appears on the monitor screen other than the default monitor splash.

try swapping the ram to different slots, make sure all the plugs from the PSU to the motherboard are plugged in, double check GFX card, disconnect anything that's not required to test if the computer will work or not (disconnect extra hard drives, usb devices, optical drives)

Try this:
http://www.reddit.com/r/buildapc/com...he_essentials/

You probably don't have all the necessary power plugged in, or have a certain connection plugged in wrong.