For those of you like me who own a Thermaltake big typhoon, heres a very simple mod you can do to increase cooling significantly, reducing cpu temps 2 degrees C or more.
If you unscrew and take off the 120mm fan yoiu will see that the cooling section of fins and pipes is divided up 50;50 into 2 banks of fins, each with 3 pipes running though them.
But at the end of each bank, there is a noticable gap between the end of the fins and the fan shroud.
Airflow being what it is, it will take the path of least resistance, so a sizable amount of the airflow generated by the fan is going through these 2 holes at the end of each fin bank, and not contributing to thermal dissapation.
So just get some soft foam and squeeze it into these gaps, say a piece 1x3" and make ALL the airflow go between the fins!