Power Consumption & Temperatures
When at idle the Phenom X3 8750 (2.4GHz) uses 11.5% less power than the Phenom X4 9750 (2.4GHz), which operates at the same frequency minus the additional core.
Under load the triple-core 8750 consumed 16.5% less power, and given that it was not really much slower than the 9750 in the vast majority of tests, we have found it to be slightly more efficient. That said, under load the Phenom X3 8750 platform still consumed 53.5% more power than the Core 2 Duo E8400 system.
The power consumption levels reflected upon the operating temperatures. Both platforms were cooled by the OCZ Vendetta 2 and you will notice that the Phenom X3 series, while being slightly cooler than the X4 processors, was still quite a bit hotter than the E8400.