You need to add an extra video card when using processors that have no video support.
Core i7-8xx series (Quad Core) – no video support
Core i5-7xx series (Quad Core) – no video support
Core i5-6xx series (Dual Core) – on-board video supported
Core i3-5xx series (Dual Core) – on-board video supported
Pentium G6950 (Dual Core) – on-board video supported