Can't use monitor and gpu's full settings. What am I missing?

To start with, my 1440p monitor also says its generic.

This sounds like more of an issue with the game’s prefs file.

No your monitor is fine.

Here’s what I suggest you try first:

Go to the Documents\Diablo IV folder.

make sure you are not running Diablo IV

In here, find the file called LocalPrefs. Rename it or add a .old to the end. This will force Diablo IV to create a new file and reset in-game preferences to their defaults.

Now.

From here, you need to make sure of a few things before launching the game:

Nvidia control panel. Make sure the game isn’t using a custom game profile. Those settings may override any settings in the main nvidia settings panel. If you are using G-Sync, disable it.
Set an FPS cap in the driver of 162.
Set a background FPS cap of 60.

Windows:

Make sure the GPU has scheduling enabled and if you have an HDR monitor, enable flip presentation mode.

Also make sure the FPS here is set to 165 under Windows.

Then, once those two things are checked out and done, launch the game. You will go through the Gamma setup again.

Then you will be at the character menu. Open the settings before starting any game.

In here, under graphics:

  • Turn off vsync (this may or may not help, you can also leave it on)
  • Disable peripheral lighting
  • enable DLSS and set to quality
  • Set an FPS cap (for now) of 100FPS
  • Set background to 60FPS
  • Disable Nvidia Reflex for now.
  • Make sure the game is set to full Ultra

Under communication, disable both Crossplay features.

Once all that’s done, try it out. From here, you can increase the FPS if its stable up to no higher than 160FPS. There is no reason to run it above the monitor’s refresh anyway. You can also use Reflex to help smooth that more if needed at that point.

Here is a link to my setup that is still current for my desktop. My settings may differ somewhat from what I suggested, but that’s fine. That was due to some performance changes that I had been testing on my laptop, but as of this post, my desktop is using the below adjustments.