"I just build a computer and it starts and goes off all the time. "
Please be more specific. What do you mean by it starts? Does it POST, does it load windows or what?
When you remove the memory you say it starts, I'm assuming here you mean it POSTs OK.
Have you checked that the memory is compatible with the motherboard? The manual should list compatible RAM. Have you tried with just single sticks of RAM?
Could be a faulty MOBO if none of the RAM is working.