Retrieves power usage for this GPU in watts and its associated circuitry (e.g. memory).
For Nvidia Fermi or newer fully supported devices.
On Fermi and Kepler GPUs the reading is accurate to within +/- 5% of current power draw. On Ampere (except GA100) or newer GPUs, the API returns power averaged over 1 sec interval. On GA100 and older architectures, instantaneous power is returned.