most of the energy used by the chip is directly translated to heat. that's why there is a strong correlation between TDP and wall draw. to produce 95 watts of TDP heat, the chip draws "around" 95 watts because very little energy is actually lost through work. most of the energy is directly converted to heat.
as far as overclocking. yes you will draw more. but at the same time, unless you are running furmark/prime 24/7 the chances of you actually pulling that load on a constant basis is very low. in gaming loads, most people who do not have insane levels of OC don't actually pull too much above the TDP.
yes there are plenty of exceptions here at OCN, but that does not negate the strong correlation between the total TDP and actually power draw. from the wall.