I'm new to the world of mining rig builds and as such have a retarded question to ask.

I've just built a a rig with 7 x Sapphire 7950 Dual-X GPUs, using a Z77A-GD65 motherboard. After connecting it all up correctly and plugging the monitor into the mobo via VGA it powers up fine but I get no signal to the monitor. If I use a newer monitor with HDMI and plug into one of the cards then I get the display expected.

So am I meant to plug into the mobo or one of the cards? If the mobo what could be the cause of no signal?