Computer turns on but nothing happens

[uKiE]

I recently bought a PC in parts and had a friend put it together. I have no idea how to do repairs when i get even get the OS to come up. I went to restart my PC, when it tried to do so nothing happened. It turns on, i hear the fans but nothing comes up. I've opened the case and checked for loose wires but there are none. I read somewhere else on this forum about reseting like my bios or something. I would really appreciate some kinda help here.

Parts
Biostar SLI series MB
1 GB ram
3.0
Nvidia 6600 GT
CD Rom and DVD drive

 

[Law]

Where's your CPU on the list? Fans moving are a good indication that the PSU is working. Does the fan on the CPU or any fan on the motherboard work, any light on the motherboard? HereÂ’s what you want to do. Take out all components and leave just the CPU on the motherboard and the PSU connected for power. Boot it up and see if you get and beeps, if none that means motherboard or CPU problem.

 

[Nitestick]

common cause is that the 4 pin power connector to the motherboard has come loose

 

[OatesyX]

assuming that youve it all conected right with no parts missing try putting your ram in different slots, it worked for me a few times,