My computer starts up for a couple of seconds then it turns itself off

PLEASE READ I NEED YOUR HELP!!!
Hello,
I tried to build my computer...and i had everything conncted cpu(intel Pentium D W/fan), HDD, MOBO (abit fatal1ty) Graphics Card (ATI Radeon x1650pro 512mb) Power supply (500W) DVD ROM (samsung Spinpoint) i connected all them, then flicked the power supply.
The Fans started going the the case lit up with the leds, but, the screen was blank and after 10 seconds the computer turned itself off.
I disconnected all the components except the mobo, cpu, graphics card, powersupply. Then i turned on the powerunit and this time the bios menu came up, but after a few seconds the power went again.
Iv checked all the wires countless amount of times but no luck. I badly need help. Wat could be the problem, is the motherboard Falty?

oh not good dont turn it on again and check that there is nothing blocking the back of the mother board ( the metal case thing at the back of the mother board )

if its not that hen it may be that the motherboard is crossing over one of the pins that attach it to the back of the case and this means that you have to unscrew and lift it up to see it is.

d-shark

Thanks for help... but could you explain what you mean by something blocking the motherboard.. and what u mean by the motherboard is crossing over one of the pins.
Sorry about this but im a computer building newbie this is the first comp i ever built so my computer building knowledge is low. Thanks for the help, i was up till 4 last night trying to fix this thing. Any help is welcome

well you know where you plug in the mouse and keyboard and the USB ports at the back of the mother board well there is a shiney metal plate that covers the extra space... right still with me ... and then if one of the metal covers that align all the components sockets ( mouse, keyboard USB ports Ethernet ) is poking out the wrong way wand has gone inside the [ ethernet plug for example then that may be the problem., as it provides a quiker way to the electiricty to go round { short circut } ]

as for the other one the mother board is screwed onto the case via screws and they screw into little sockets on the case ... right ... and then if one of the sockets that you screw the screws into,is underneath the motherboard and this crosses the pins on the bottom that are the left over bits of solder used to fix the compontents down then this to may short circut the board and this is probalby why your computer turns of after a 10 seconds as to not short ciruit itself.

d-shark


RAM you didnt mention any ram in your first post and this to may also be an issue so get back soon, you got me wondering now...

Cheers for that simplified (4yr old child version text)...much appreciated. lol. Just to clarify i got ram 1 gb pc4200 seems to work fine. Ill check for those now and get back to u if it worked. Ttyl

nope i checked that and it wasnt touching the backplate or the screws werent interferring with any pins. so do have other iideas to what the problem could be?

well no not really sorry, one of the master forum people might help you but i cant that is about all the knowlodge i have on this just know.

d-shark

Unplug everything from the motherboard except the CPU, RAM and power to the motherboard.

Remove any sound-cards, modems, basically go right back to basics, you don't even need the hard drive plugged in.

See how you get on, if it still turns itself off check the motherboard isn't shorting out on the case, remove the motherboard and test it on a bench if necessary.

Other things to check are that you have definitely put the heat-sink and fan on the processor properly and if the PSU isn't new then try a new one.

Failing all that get the motherboard swapped out for a new one also.

Thanks for all the help!!
Well the problem for it not starting up was that the cpu fan wasnt in properly. Total Newbie mistake.. my bad BUT.....
I have a new poblem when i start it up after about 30 mins the power goes. Im thinking it is the powersupply but i do have a 500W sorce i thought that wud b more than enough here are my specs

Abit Fal1ty mobo
Ati Radeon x1650pro 512mb Graphics Card
Intle Pentium D 3.0 ghz
1gb pc4200 ram

Is 500W enough to support that???
And i googled the Graphics card and that says it takes 450W of electricity..surely that couldnt b correct??
Cheers for any help... thanks D-shark for your help

You may have cooked your processor.

Continually turning on a PC without the proper cooling is not good, CPUs are very sensitive.

The theory is that not having the fan on has damaged it, although it works, after 30 Min's the core has warmed up to a point where it becomes unstable.

Same advice, remove everything, even the graphics card and use the on-board graphics, see if it's any better.

Well i redid everything and just left the cpu,ram,graphics card, power suplly, hdd in the mobo. I turned it on and it worked perfectly!!! :L :L I left it on overnight and it was stiill running!!
But when i came back to it this morning and connected the LEDS,fans etc..... the computer rurned it self off after around 20mins!!! I have a 500W PSU is that not enough...the case i have is a 3d Aurora...IT A huge CASE!!

Well, go back to basics, add the other bits one by one.

When it crashes, you'll know what part is causing it.

Sounds like all the major power-usage components are already in Dave.

Good advice on reconnecting whats left one by one, but i'm thinking this could be/also be power related.

David: Is this a generic power supply? (grey unit, etc) Do you know the make and model of this unit?

The reason I ask is because, generally, generic brand psu's are nowhere near as stable or efficient as the higher end one's.

As an example Coolermaster, Enermax, FSP and so on psu's are around 82-85% efficient which means one of their 500w psu's, when running at peak (500w) will draw between 575-590w from the mains.

Generic psu's are usually around 50% efficient, so a 500w psu will draw 1000w from the mains to to reach peak. Fuel bills anyone? Also, and more worrying if you've a generic psu pulling 1kw through it's innards, chances are it's going to fail as they aren't built for that kind of heat generated by all that electricity.

This doesn't necessarily apply in your case as the psu may also (as generic psu's generally aren't) not be very stable.

Each line out from the psu (12v, 5v etc) will out a certain amount of amps, if this isn't stable and falls below the ATX specification at any point (each line has to reach a certain amount of ampage to match this spec) then the particular component the line is connected to may fail due to lack of power as each component is 'expecting' a certain amount of power so it can work.

And no, a X1650 does not need over 400w to run, nowhere near infact.

well the fact that it goes on for 30 mins and turns itself off is a problem one way to see if the computer is overheating is to go into the bios and watch the core temperature of you computer ( i think its the third heading ) and if it reaches about 70 degrees celcvuis then the processor shoiuld turn its self off and shut down to stop its self cooking.

so try that and the 500 W should be enough ... easily.

After 30 Min's its overheating, the self protect cuts in and instant power off.

From experience I'm 99% sure you have cooked the processor. Period.