AfterBurner has to be running after the reboot. Did you set it to run at startup? Just look and see if your overclock settings are still there in AfterBurner after the reboot. If not, I guess you didn't save them.
If I open up Afterburner, I don't see any options for my cards. The 4 GPU Cards show up but everything is greyed out and I can't change any settings.