Just built computer doesn't boot

[charlieko]

I just built a computer and it doesn't boot!
It doesn't show anything on the screen either, so I installed a POST code reader and tried to see what went wrong.
However, when I turn it on, the POST code reader shows some codes for about a half second and then turns to "--".
Also, the clock LED goes off.
(Everything happens so quickly that I can't read what the last code was)
I'm not sure if its motherboard's fault or power supply's.  
The BIOS is AMI and both the motherboard and power supply are pretty much of inferior quality.  But I'm so poor to replace them.
Can somebody help me identify what the problem is? And what I should do?
Thanks.

[GX1_Man]

The BIOS is AMI and both the motherboard and power supply are pretty much of inferior quality.

Can somebody help me identify what the problem is? And what I should do?

The answer is apparent.

I am sure that it is not assembled correctly assuming the above statements are not the only issues.

[rrsg1]

try looking at the small thin wires that are connected the the power and reset connections. Make sure the contacts are properly in place, positive and negative can make a difference. Most mobo's have directions to help with this. I know all abut missing that BSoD and other screens that come up way too fast. Heres a tip. Sometimes i videotape the screen and i can look back and kinda read the problem.

The newest issue of Maximum PC has a great article all about Blue Screens of Death, I learned a lot about them. Like for instance, the main problem is usually towards the top of the screen, and its usually a single line description.