New monitor

I have installed a new Monitor, AOV I12369Vm and connected through hdmi cabe at the available Graphic card (zotac-Nvidia 650) end of the system. That was working perfectly ...
Now I wanted to remove the graphic card for some reason and wanted to run my system with on board graphic card ( System with intel core i5 , 4gb ram, win7 64 bit).
After properly shutting down, i removed the Graphic card and connected the Monitor Hdmi cable in the available given mother board slot. Now the system gives a beep sound, starts and stops.
i also removed the n nvidia display drivers .
the system starts but no signal to the monitor.
The computer works normally only again after i insert the graphic card and connect the monitor hdmi cable through graphic card.
I want to run the system normally without graphic card and with monitor connected to mother board slots.