Initial state: 392.00/1.3.36.6 (from NVidia WHQL) currently installed before starting today's research.
First step is to "upgrade" (with NO HDMI CABLE CONNECTED) to 398.36/1.3.37.4 (from Lenovo), leaving the "clean install" option un-checked. So whatever was present from 392.00 and not upgraded through 398.36 should remain installed and configured just as-is. This driver install is performed only with the laptop screen active.
So before upgrading to 398.36/1.3.37.4 the current 392.00/1.3.36.6 state of things looks as follows (again, no HDMI cable connected and only the laptop screen is being used):
(a) Device Manager, note that NVidia HD Audio Device shows in "sound" along with Realtek. This will result in four NVidia digital audio device options appearing (as "not connected" since there is no HDMI cable connected) in Playback Devices.

(b) Playback Devices (note that it still shows Oppo 203 which is how I was previously set up, although for today I'm simply going to connect HDMI directly to my LG TV):

I then ran the "upgrade" from 392.00/1.3.36.6 to 398.36/1.3.37.4 (i.e. left un-checked the "clean install" option):
(a) install options:

(b) installation complete:

(c) After re-booting, and still with NO HDMI CABLE CONNECTED, Device Manager seems to show a hybrid combination of the leftover marks of 392.00/1.3.36.6 and the new 398.36/1.3.37.4. In particular, there is still the NVidia HD Audio Device shown in Device Manager Sounds and it even shows driver version 1.3.37.4.

And Playback Devices still shows all four of the NVidia digital audio devices. (although the previous Oppo 203 which was shown has been reset to the default):

I then shut down in order to connect an HDMI cable from the P70 to my LG OLED TV. I then re-booted, and had to turn the TV on in order to display video output. As previously mentioned my laptop screen had previously been disabled so that I could run only with external Eizo monitor (i.e. "display only on 2"), and this setting seemed to apply when my external display was now the LG TV. So the laptop screen was dark, but video was going to the LG TV.
However the process of connecting the HDMI cable seems to have reset the NVidia HD Audio Device in Device Manager "sounds", so that it no longer appears.

And this, in turn, caused the disappearance of all of the NVidia digital audio devices from Playback Devices:

Note that in Nvidia Control Panel we see anomalous indicators. The LG TV is presented as an available as an HDMI Audio device, but in fact this is not the case as proven by Playback Devices.

And as stated earlier, for some reason the laptop screen is not shown as (1) in the "set up multiple displays" dialog of NVidia Control Panel. Only the LG TV is shown as (2), although Physx clearly knows the laptop screen is present. This anomaly makes it impossible to activate my laptop screen in order to "duplicate these displays" in order to present the same content on both screens simultaneously.


I don't know why the laptop screen (1) defect appears with 398.36 of the graphics driver, but it does. As will be proven in the next set of duplicate experiments reverting back to 389.08, NONE OF THESE DEFECTS OR ANOMALIES OCCURS USING 389.08/1.3.36.6!!! Everything tried with 398.36/1.3.37.4 and that fails or behaves strangely instead works perfectly with 389.05/1.3.36.6.