The key feature of the lower power Phenoms is the reduction in Thermal Design power (TDP) from 95W to 65W which is a significant drop in anyone's book. AMD has made this improvement in heat output essentially by reducing the clock speed, which means a lower voltage and thus less power is required to keep the chip running. AMD didn't have a clean sheet of paper when it designed the Phenom 9350e. On the one hand it was constrained by the performance of the low power dual core Athlon X2 4850e which runs at 2.5GHz with a TDP of 45W. It was essential that the low power quad core Phenom would out-perform the Athlon X2.