Not sure, playing around with 'Power Management Mode' within Nvidia's control panel, I noticed that an idle Skype could bring the card upto ~1585 when 'Prefer Maximum Performance' was selected.
If you don't use all the bloatware that is included in the drivers, just install the bare minimum. Manually extract (using 7-zip or similar) the following folders
Display Driver,
HDAudio,
NV12 and
PhysX along with the following files
EULA.txt,
ListDevices.txt,
setup.cfg and
setup.exe. Then just run setup.exe to install. No more bloatware, no more geforce experiance and no more telemetry.
Edit: Found the old jpg -