Well you never know. It might give you maybe an extra 50MHz or more just never can tell. You'll need to take precautions for condensation maybe a Leufkens peltier kit. At any rate it'll make your CPU live longer because of the lower temperatures. Well hope that helps.
IMHO running a peltier is extreme cooling ,I would say that lees than a 10% possible O/C is not worth the price or the risk involved ,there are chips that benefit greatly from extreme cooling however the C2-566 is not one of them