My setup is as follows:
Windows 8.1 HD Graphics 4600 video bios 2170 driver 10.18.10.3412
I have a ASUS H87I-PLUS with a Intel Core i7-4770S (HD4600)
The DVI port is connected to my ASUS VN248H monitor.
The HDMI port is connected to a Yamaha RX-V375 reciever and then to a BenQ W1070 Projector
The DVI/Asus monitor is set as primary display.
I have a couple of issues, but his is the biggest one:
If I turn off either the Benq or the Yamaha (HDMI), my DVI port with Asus monitor also goes blank, leaving me without display.
If both monitor and reciever/projector is on, I turn off the projector, my monitor goes blank. Turning off the reciever and on again will restore my monitor !! (even though they are not connected). So the HDMI port needs an "active" connection for the DVI to work.