Can't get a signal from pc to monitor or tv.

[xeloth12]

I just bought a Gigabyte R7 260x Radeon gpu, just put everything together last night. Everything is powered up, but it doesn't send a signal to the monitor. Tried it on my old desktop and it showed a picture with no problem. Connected the monitor to my laptop and it worked as well. I'm at a loss here on why it won't work in my new desktop. Could it be the motherboard is bad?

 

[xeloth12]

I also have no os on the desktop yet. or any drivers for the computer.