Power Consumption & Undervolting

The world is in a recession. Many people are getting laid off and having to cut back on their expenses. Some users out there might be looking to save some money on their monthly electricity bill and they will definitely be interested in the power usage of this platform. But I am also interested in reducing the voltage on the CPU to see how low it can go.

AMD’s Cool&Quiet and C1E power saving technologies were enabled.

The lowest voltage the PC was stable was at 1.1V which is normal Vcore-0.2V. The stability was tested by running Cinebench R10 xCPU bench and a game at the same time.

Here are the CPU-Z screens of undervolted idle and load states.

Note the voltages in this test (measured in Windows) :

Athlon II X2 250

• Overclocked (Cool&Quiet disabled) : CPU Vcore (Idle&Load) 1.475V, RAM 1.8V, NB +0.75V, all other voltages normal
• Undervolted (Cool&Quiet enabled) : CPU Vcore Idle/Load 0.768V/1.125V, RAM 1.5V, all other voltages normal
• Normal Voltage (Cool&Quiet enabled) : CPU Vcore Idle/Load 0.992V/1.35V, RAM 1.5V, all other voltages normal

Phenom II X2 550

• Overclocked (Cool&Quiet disabled) : CPU Vcore (Idle&Load) 1.504V, RAM 1.8V, NB +0.1V, all other voltages normal
• Undervolted (Cool&Quiet enabled) : CPU Vcore Idle/Load 0.752V/1.104V, RAM 1.5V, all other voltages normal
• Normal Voltage (Cool&Quiet enabled) : CPU Vcore Idle/Load 0.944V/1.296V, RAM 1.5V, all other voltages normal

Although we don’t see a big difference at normal and undervolted states in idle mode between the two CPUs, we see a 10W or greater difference due to presence of the L3 cache on the Phenom II X2 550. Once overclocked, the Phenom II X2 550 consumes a lot more power than the Athlon II X2 250.