Are you nuts, or do you actually have an explanation behind that ridiculous statement?

Are you seeing temperatures in cgminer? If not your cards are likely not using any of your clock settings you are asking for. I'd imagine your hashrate would be right about where it is now, on stock clocks.

Try mining locally, with a display.

FWIW I still have this problem with my 280x cards in xubuntu, I can not start mining over ssh/putty.