nix/modules/system/hardware/nvidia.nix

{ config, lib, pkgs, nixpkgs, ... }:

{
  nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
    "nvidia-x11"
    "nvidia-settings"
  ];

  hardware.opengl = {
    enable = true;
    driSupport = true;
    driSupport32Bit = true;
  };

  services.xserver.videoDrivers = ["nvidia"]; # or "nvidiaLegacy470 etc.

  hardware.nvidia = {

    modesetting.enable = true;

    powerManagement.enable = false;

    # Fine-grained power management. Turns off GPU when not in use.
    # Experimental and only works on modern Nvidia GPUs (Turing or newer).
    powerManagement.finegrained = false;

    # Use the NVidia open source kernel module (not to be confused with the
    # independent third-party "nouveau" open source driver).
    # Support is limited to the Turing and later architectures. Full list of 
    # supported GPUs is at: 
    # https://github.com/NVIDIA/open-gpu-kernel-modules#compatible-gpus 
    # Only available from driver 515.43.04+
    # Currently alpha-quality/buggy, so false is currently the recommended setting.
    open = false;
    nvidiaSettings = true;

    package = config.boot.kernelPackages.nvidiaPackages.stable;
  };
}