If you have a 400 series card this is normal.  When you use the 470/480 you should just see processor clock.  If you are using one of the standard skins you will see that core clock is greyed out and cannot be adjust.  Shader clock should be available and adjustable.  When you adjust the shader clock it will also adjust the core clock.  If using the 400 series skins when adjust processor clock you should be both will adjust together.  The Core clock will always be 1/2 the shader clock.

Below are pictures of what you can expect.

470 skin.  Processor clock is available and can be used to adjust both Shader and Core clocks.

480 skin.  Processor clock is available and can be used to adjust both Shader and Core clocks.

Classic Skin.  Core clock greyed out and no reading in the box.  Shader clock can be adjusted however.