Asus p5n sli problem

[mou99]

Hello,my Asus p5n sli motherboard doesn't start,beep and display.what to do I am very confuse,please some body help me and tell me cause.

My spec. Is...

Asus p5n sli
Intel p4 3.0 GHz 631
Nvidia GeForce 210 1gb DDR3
2gb ram DDR2
450 watt.power supply

Please help me!

 

[mou99]

No buddy help me?