How to build a computer - that works?

by Ryan
(USA)

Okay. So I took some components from an old computer and am trying to build a new one. I have a new 500w power supply, a new disc drive, a new case, a new Gigabyte ATX micro Motherboard, and I am using old DDR2 RAM (4 GB, which the MoBo says it supports) and an old HD.

I tried booting up without the drives or the HD attached. Everything powers on fine, the fans spin, I get one beep. Then invariably at some point, the computer loses power. The power loss comes at different times. Sometimes almost right away, sometimes I make it to the Windows XP or BIOS screen (but never further, it always crashes almost instantly). I don't have a CPU cooling fan, but I have the power one and the system one. I don't think that's the problem, but I'm running out of ideas here.