Thanks for joining the Graphics community.
I understand your computer is unable to detect Intel® Graphics Controller.
Vasco's comment is right. The onboard graphics solution is disabled electronically at BIOS level when you install an external video card.
Please check with Asus for BIOS settings that allows onboard graphics and video card work at same time.
This worked for me on an Asus Maximus VII Hero motherboard.
BIOS -> Advaced -> System Agent Configuration -> Graphics Configuration
Changed Primary Display to "CPU Graphics"
Changed CPU Graphics Multi Monitor to "Enabled"
This enabled the intel on board graphics and I was able to use NVIDIA GTX 660 as well.