You probably have an on board graphics chip and the BIOS is probably defaulted to that. You won't know until you can get some RAM installed properly and plug the monitor into the MB GPU output. At that point you can enter the BIOS and change the active GPU to the PCI selection. When you re-boot you will have to have moved the monitor input to the GPU board. If it still doesn't play it's probably a bad board or power supply. Replacing individual components with known good ones is the only way to troubleshoot.