RivaTuner can use either exports from NVIDIA tweaking library or direct access to the display driver via ExtEscape calls. By default RivaTuner uses ExtEscape calls for the Detonator 12.90 or higher and exports from the tweaking library for the rest drivers to query and set clock frequencies in realtime.
You may set this value to 0 to force RivaTuner to use the exported functions or set it to 1 to force it to use ExtEscape calls.

