Computer turns off after turning it on

[sirreg]

I changed my motherboard and memory and cpu - I used my hard drive with windows xp from my previous system. I have upgraded to the new hyper threading 800 fsb. 302 cpu and 2 256 ram.
when I got the machine together I hit the power button and it turns on for a second or two then powers it self off. So I am thinking that is for a safety reason. Any ideas? Alos will my operating system work when I switch out that much stuff or will I have to call microsoft to get them to reregister my xp?
thanks Roger

[dunbar]

Welcome to techimo!
Possible Powersupply issue - how big is the current PSU?

[Bill in SD, CA]

Hi, Welcome to TechIMO!

Just a thought - you might want to try reseating all your cards, memeory, and power and cable connections and see if that's the problem. Failing that, I would try removing all cards except for video and memory just to see if you can get to POST. If that works, I would then put the cards back in one at a time.

The XP thing - I've heard it go both ways.

Dunbar has a point.

Good luck,

Bill

[sirreg]

Yes I am going to try all those things - the power supply is a 400
I have the Alien ware type case. I have did some research and one reason that comes up alot is that when the computer turns on then shuts down is a safety feature built in the motherboard and checks to make sure the fan is working anc cooling the processor. So the first thing I need to check if I have the processor fan hooked up correctly. If so I will start with each card and work from there. Thanks again.