Elitebook 8440P no sound via HDMI / Display port

[JC101]

HP8440P Win 10 NVIDIA NVS 3100M display card. Picture but no sound to TV via HDMI

Device manager shows HD Audio Device (MS 4/9/19 10.0.18362.356) and 4xNvidia HD Audio devices (14/11/2016 1.3.30.1)

In thread https://h30434.www3.hp.com/t5/Notebook-Video-Display-and-Touch/Has-DisplayPort-to-HDMI-Audio-Out-Pro...
Lucas aka XyZnyc suggested installing the drivers i sp47020.exe
This containes NVIDIA driver english version 14.0.0.162
But the audio drivers will not install. Even if I tell Device Manager to update from the HD Audio directory it says best drivers already installed

If I uninstall the HD Audio Device and try to install SP47020.exe the screen flashes (so I presume the graphics drivers are installed) but the NVIDIA HD audio has the same version number and date (so presumably never got installed) and the HD Audio device is still missing and the sound does not work. I also lost the ability to duplicate the laptop screen on the remote TV

So I uninstalled the graphics device. Rebooted and video works fine (PC and TV)
A new sound device has appeared (Toshiba TV-1 excellent its a Toshia TV) but its greyed out and listed as not plugged in)

So any ideas as to what I might try next?

[JC101 · Accepted solution]

So the answer for me was to use the Vista graphics drivers from the 8440p support page

Its the NVIDIA NVS 3100M Vista x64 307.83 driver and downloads as sp61073

Select advanced so you can do a 'clean install'

Good Luck