Compared to the regular GeForce 9600 GT, the core clockspeed dropped from 650MHz to 600MHz while the shaders dropped from 1625MHz to 1500MHz. Together with a voltage drop from 1.1V to 1.0V and a couple of other changes, the new version manages to cut the power consumption from 96W to 59W.
GeForce 9600GT Green Edition is quite similar to GeForce 9600GT in specification, except for a little bit reduction in frequency. The core/shader clock has dropped from 650/1625MHz to 600/1500MHz respectively, while the memory clock keeps unchanged at 900MHz.
Besides, its voltage has reduced from previous 1.1V to 1.0V, and the power consumption falls from 96W to 59W. The external power connector has been removed.