Kabylake 7Y75 , HD 615 not changing brightness of embedded display port monitor in ultrabook . Win Ver 1909. No access to BIOS power management . Brightness slider IS present. Latest Intel driver from 11/14/2019. Where to look to fix in regedit?

[SFree2]

\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000 > FeatureTestControl tried values > f008 , f002 , f280 , ffff

No OEM drivers or support.

[AlHill]

So, going straight to the registry, eh?

Before you mess around in the registry and really screw something up, provide some information:

What version of Windows 10 are you running? 1903 (with all updates)? 1909?

What is the model number of your laptop?

Are you using the drivers provided by the laptop manufacturer?

Do you have dual graphics?

Also, put the registry value back to its original value.

Doc

[n_scott_pearson]

I agree with Al. The most common cause of this issue is installation of Intel's standard driver package onto a laptop that requires a customized version to support features like brightness control, switching between graphics engines, etc.

Just saying,

...S