Comp Boots; Blank Screen

[partypat]

I just put together a new decent computer for my old lady so she will stay off mine, well everything boots up and starts but the screen stays blank. What could be the problem? If you need more info just ask.

Specs:
Amd 4600+ x2
Gigabyte GA-M55plus-S3G (AM2)
Corsair XMS2 DDR2 (2 1024mb)
Maxtor Hard Drive SATA
evga nVidia 7900 GT KO (not installed)
500 watt psu

 

[Tedster]

is your graphics card plugged in?

 

[partypat]

No the graphics card is not plugged in. I have the monitor connected to the motherboard.

 

[riekmaharg2]

Does your computer beep when you turn it on. If it does post what type of beep it is. If it doesn't beep try resetting the bios. If it still doesn't work try unplugging everything inside your comp apart from motherboard,cpu,memory,psu, then see if it works.