It's unfortunate that you have this issue, please try the following;
Install the Intel Chipset Driver from this link Z97-A | Motherboards | ASUS Global, click on ''Chipset'' and install the latest version, once installed restart your computer.
Then, install Intel Management Engine Interface Driver from this link http://www.asus.com/Motherboards/Z97A/HelpDesk_Download/, click on ''Chipset'' and install the latest version, once installed restart your computer.
Finally try installing Intel® Iris™, Iris™ Pro, and HD Graphics Production Driver for Windows® 7, 8.1, & 10 driver again Intel® Download Center.
I would also recommend contacting ASUS in order to get the driver for the switchable graphics.
Let me know your findings.
I have tried both with the ASUS recommended chipset driver (v184.108.40.206) and the latest Intel one (v220.127.116.11), but I've had no success so far.
The automatic driver update tool by Intel hasn't brought anything up either and I'm starting to wonder whether the graphics adapter is even read by the system. I will contact ASUS and investigate further.
It turns out that at some point during the installation of Windows 10 my system detected the presence of my GTX 980 and automatically switched off the onboard vga in the BIOS. I changed it back manually and hope my PC doesn't decide to get smart again.
Thanks again for your help, I'm sorry if I wasted your time, not exactly used to these new smart motherboards I guess.
I'll close the thread, have a good day!