Sir, I am building a new pc with i3-4150 processor and mobo (GA H81M S). Processor having inbuilt 1.7GB graphics. if i am adding 1 GB external graphics can i get both graphics (1.7GB+1GB=2.7GB) ? and also my mobo don't have HDMI port. HDMI port is it important or not?

Pls clarify..