I have a 5th gen carbon X1 (Intel HD Graphics 620) driving a BenQ PD2710QC through USB-C. I'm trying to connect an HD projector through the HDMI port. Most often, when I connect the projector, the display flickers on and off several times and I'm not able to get it to work--the machine is mostly unusable until I disconnect the HDMI connection.

However, if the system is stable long enough for me to set the refresh rate on the display connected to the HDMI port, and I reduce it 24p, everything works fine for the rest of the session.

The problem is it defaults back to 60p and I'm not able to access video controls (either the Windows 10 display settings or the Intel HD Graphics Control Panel) for long enough to drop the refresh rate before the display goes into a flashing/non-functional made that renders the laptop inoperable until the HDMI cable is unplugged.

Is there some way I can force Windows 10 to only output 24p prior to connecting the display to the HDMI port? The control panel only exposes that second display after it is connected, which is generally too late to fix it. Is this something that can be set in the registry? Or should I be looking for a special setting in the Intel Graphics Control Panel?

(As a side note, since I'm generally playing movies on the HDMI port to the HD projector, I don't mind the slower refresh rate.)