AMD Phenom II X4 940 Processor Review

Power Consumption and Voltage Scaling

Power consumption was measured at the powersupply with a Kill-a-watt power meter. Idle was the recorded value after booting Windows Vista and giving the system 15 minutes to settle with zero CPU utilization. 100% load was the recorded average of three runs of running wPrime 1024M with 8 threads and two instances of SuperPi 32M to insure 100% CPU utilization. Two thread load was the recorded average of three runs of running wPrime 1024M with 2 threads with the affinity fixed to two cores and a Super Pi 32M instance with affinity fixed to the same two cores.

I was modestly surprised by the Phenom II power consumption numbers. Phenom was a powerhog but even with the “high” 1.30v CPU the processor’s power consumption was surprisingly low. The 100% load for Phenom II was just a hair above the idle voltage for Core i7. It should be noted though that EIST was disabled on the Core i7 system as Cool n’ Quiet failed to function on the Phenom II system. However, even with power saving systems in place, Phenom II would still sip power compared to Core i7.