It should be pretty straight forward with the latest Nvidia mobile drivers. No need for ATI tool, rivatuner or Ntune.
Load up the Nvidia Control Panel then goto the Performance tab. You can unlock this section by agreeing to the terms & conditions. After that you wil get to a window displaying sliders for core/memory/shaders etc, click 'custom' and then move the sliders to the desired clocks. Then click 'apply'.
If your settings are too high they will reset, you just have to tweak a bit and then test with 3dmark or a similiar program
Load up the Nvidia Control Panel then goto the Performance tab. You can unlock this section by agreeing to the terms & conditions. After that you wil get to a window displaying sliders for core/memory/shaders etc, click 'custom' and then move the sliders to the desired clocks. Then click 'apply'.
If your settings are too high they will reset, you just have to tweak a bit and then test with 3dmark or a similiar program