You can do that with Nvidia control panel and the this download, system tools.
This integrates with the nvidia control panel and starts with windows every time.
So its not as if there is anything 'extra' like other programs , that might add other variables, with driver interaction.http://www.nvidia.com/object/nvidia_system_tools_6.06.html
Set a profile, whatever clock you decide and have it start with windows.
At least do this at first , before sending away your card for weeks