I was under the impression that you need a dvd player or dvd write drive to read dvd games, and if HL2 was in dvd format it wouldn't be 5 cds would it?
Well. The stock heatsink that comes in the retail box is usually designed to be sufficient to dissipate the heat generated when the CPU is running "normally". When u overclock and such, the stock heatsink usually can't dissipate the heat energy as fast as it's generated on the CPU. Therefore, the temperature also rises as a consequence. So u need a better heatsink/fan that is more effective at dropping the temperature.