To lower the temperature of your processor you can do the following.

1) Lower voltage
2) Lower clock speed
3) lower ambient temperature (Are you playing in a nice air conditioned room? 70F? Or just letting it get very hot?)
4) Upgrade your heatsink and/or thermal paste.
5) Increase airflow in the case.

IMO try out 1 & 2 since its free. If you dont notice much of a performance decrease go with that.
Item 3 if you are playing in very hot conditions
Item 4 & 5 if all else fails since it will cost you some money.