No monitor output when computer is on

[bzmwx9]

I have this problem every time I turn off or restart my computer, when it boots up everything seams to work fine..ie..fans on, goes through the start up hear the drive cycle...the only problem is that the monitor doesn't recieve a signal. I have switched monitors and the same thing happens. Their is no beeps or anything. Most of the time if I unplug the computer and let it sit it will come back on when I start it up. I but this computer together myself. please help

 

[Tmagic650]

Possible bad motherboard? Or video card...