Which change did you apply?

Did you use the latest AMD drivers directly from AMD, or do you use the DELL supplied version?

You should be able to change the GPU frequency and memory frequency, and save it to a profile after you applied it.

the power limit and voltage are typically locked on Alienware cards, but you could always give it a try.

So there is no way to do any overclocking? 

Some of the settings are locked by the Dell vbios.