built a new computer today and need help

i built a new a new computer today when i push power it all turns on but nothing shows up on the screen and the computer shuts off about 30 seconds after i push power please help

 

Open the box and recheck all connections as well as motherboard
jumpers (if any)
If it still fails, try one stick of memory, HD and video,
nothing else.

 

i got the computer to stay on but nothing shows up on the monitor

 

Any beeps when you turn it on? Anything more than one beep is
some sort of error.
On board video ?

 

(it dont beep) i do not think there is on board video but i put a 512mb card

 

disconnect all cables to drives. remove all cards except videocard. reseat the videocard & ram. make certain the cmos jumper is in default position according to motherboard manual.

 

thank you it worked