1) Monitor plugged into the VGA connector on the motherboard, (Rear Panel), you should get a display.
This is with the proper settings in BIOS.
Reset BIOS back to the factory default settings, and clear CMOS Error Codes.
Unplug the computer from power. (Monitor plugged into VGA connector on motherboard. No graphics card installed)
Press the Power On button in, and hold it in for a count of 5 seconds. (Count 1001, 1002, 1003, etc.)
Let go of the Power On button.
Do this procedure 2 more times.
Plug the computer back into power, wait 1 minute, turn the computer on.
If you get OnBoard graphics now is the time to install the drivers for the graphics card.
Then close all windows, turn the computer off, unplug from power.
OBSERVE Anti-Static Precautions and physically install the graphics card.
Time to enter BIOS Setup, and see what graphics settings you have.
(When the post screen comes up press the F2 key)
On the main page use the Right Arrow key to highlight - Advanced - at the top of the screen.
Press the Enter key.
Use the Down Arrow key to highlight - Chipset Configuration
Press the Enter key.
Initiate Graphics Driver should have - PCIE - to the right of it.
This stands for PCI Express. This is the factory default setting.
Internal Graphics Mode Select should have - Auto - to the right of it.
With it set to Auto;
The OnBoard graphics will be automatically disabled when a graphics card is installed.
The OnBoard graphics will be enabled when a graphics card is Not installed.
This is the download page from AsRock Support, for the User Manual for the AsRock ConRoe 945G DVI motherboard,http://www.asrock.com/mb/manual.asp?Model=ConRoe945G-DVI
On this page click on Click Here to the right of User Manual, after you have chosen what country that is nearest yours.
Allow time for the PDF file to download. (Sometimes up to 30 seconds, and additional time may be needed to fully download the file)
I would also like to know what Power Supply you're using, and if you are sure beyond a doubt that it is a Good unit.