Computer turns on for half a second and then shuts off

This is what happened when I went to turn on my computer this morning. I turn the power button on the front on and all fans begin to turn(power supply fan, case fan, cpu fan, and video card fan) and dont even make it a full rotation before turning off completely. Basically they all just kind of spin a quarter of the way and stop. So what seems to be happening is the computer starts up and something shorts out cutting the power immediately. Clicking the power button again after this does nothing until I flip the switch on the back of the power supply off and back on. Hit the power button on the front again and the same thing listed above happens.
Computer Specs:
400 Watt Power Supply
AMD Dual Core 4800+
3 gigs memory
Geforce 8800 GT

Some problems I have had since building this computer is that sometimes my video would get very slow after a while and then image becomes distorted (frames go down considerably and eventually random shapes appear all over the screen and I have to restart the computer to continue playing). Kind of odd when my video card is top of the line(at least when I bought it for 300 dollars). Im thinking that a 400 watt power supply maybe was not high enough for this machine and that maybe that has shit the bed. I really hope its a cheap fix like that and not a more serious hardware issue such as the motherboard. I have made sure everything is seated on the board properly and all connectors are plugged in securely and I am really having a hard time figuring out what is wrong with it and what probably needs replacing.

 

I would suspect the power supply. Do you have a spare or can you borrow one?

E

 

I took everything out of the case and currently only have the motherboard with the power supply connected to it. I have the same problem happen. Here is a video to better illustrate what happens when i try to power it on.
http://www.yablo420.com/computerissue.wmv

 

*bump*

 

Bump for What? someone else to tell you your PSU is poo...

O.K.
Your PSU is probably Dead.........
400w is too small for your Spec.. Just an FYI, what matters most is Amps not Watts, I can think of Not one single "400w PSU" that I would run a system of your Specs with...
________________________________________________________________
When a PSU dies it Can Kill other Hardware too...
_______________________________________________________________
Reading your other problems, you most likely were having Heat issues too



________________________________________________________________
Funny one would buy top of line VC then spend nothing on a underpowered PSU
________________________________________________________________

You can test your PSU to confirm what has been suggested, use a Multi-meter...

 

im a newb here and was about to post this same thing.. its happening to me on my dell dimension 3000.. powers up for about 10 secs then dies.. i was told it was short on ram.. currently running 256.. bought 512 same result. im wondering if its the power supply.. but im no computer guy so im not sure if bad power supplies power up and then die.. or if its bad does it just not turn on all together.. can any 1 chime in.. also what is a PSU?? Power Supply Unit?? just guessing not sure like i said if this was a car or an engine i would have figured it out.. but computers are not my thing.. thanks for any help on this as i want to fix it myself for the cheapest amt of $ possible.

 

ok thanks guys i will buy a new PSU.. i dont really care to spend $ for a high end one like the one u like.. i was thinking of just going on ebay and picking up another stock dell one for about 20 bucks? anything wrong with that??

 

Your PSU powers everything your computer does. Don't skimp on that. The PSU is the, or one of, the most important componants in your computer. And it has the distinction of being able to fry hard drives motherboards, video cards and such if it dies. It can also send you on a long confusing path to find out why the machine craches. I learned this the hard way.

Buy what you want, get what you pay for. Just my advice. Best of luck to you. This one has good reviews, I have not used it. http://www.newegg.com/Product/Product.aspx?Item=N82E16817189005

E

 

thanks for your knowldge and advice.. i'll consider getting a better one.. trust me i know what u mean , u get what you pay for thats how it is when modding a car.. i will see if i can get a better one. quick question though is that one u suggest external?? or does it fit in my tower like a stock one? and how do i know if this one workds with my pc?? i know nothing about specs.. mine is 250watts this one is 500watts is it compatible will it work ect how do i know.. i dont want to order something that wont work with my machine...

 

Both fit in an ATX case. An ATX one should work, just check for SATA, and other stuff that needs a different plug.

E