Our Phenom II X4 920 performance tests showed that it may be a very good choice for an overclocker platform. But before we draw any final conclusions, let’s see if it turns out as power-efficient as Intel CPUs. So, we measured the power consumption of a system (without the monitor) built around AMD Phenom II X4 920 in its nominal mode and during overclocking and compared these results against similar platforms built with Intel CPUs from the same price range, namely, Core 2 Quad Q8300, Core 2 Quad Q9300 and Core 2 Quad Q6600.
During this test session we loaded the CPUs using Prime95 utility. Besides, we activated all power-saving technologies, such as C1E, Cool’n’Quiet and Enhanced Intel SpeedStep, to make sure that the power readings in idle mode were correct. It is important to remember that Enhanced Intel SpeedStep is implemented in such a way that during overclocking it doesn’t change the processor core voltage, but still lowers their frequency under low workload. AMD Cool’n’Quiet technology, however, is fully operational even in an overclocked system.
Phenom II X4 920
Core 2 Quad Q6600
Core 2 Quad Q8300
Core 2 Quad Q9300
Phenom II X4 920 @ 3.72GHz
Core 2 Quad Q6600 @ 3.6GHz
Core 2 Quad Q8300 @ 3.56GHz
Core 2 Quad Q9300 @ 3.56GHz
Unfortunately, new AMD processors still lose to alternatives from Intel even though they are now manufactured with more advanced 45nm process. Even in nominal mode a system on Phenom II X4 920 processor consumes 20-30 W more than similarly performing platforms on Intel CPUs. In fact, power-efficiency of the new Phenom II X4 processors improved only compared to the previous-generation quad-core Intel processors manufactured with 65nm process that are still widely available in retail.
During overclocking, the situation is not any better for AMD offering. Although Phenom II X4 920 boasts fully operational Cool’n’Quiet technology in overclocked mode, even in idle mode the system built on it consumes more power than Core 2 Quad Q8300 and Q9300 based platforms. When the CPU utilization hits 100%, the power consumption difference turns more than serious and reaches 70-80 W. Moreover, power consumption of an overclocked Phenom II X4 920 based system is almost the same as that of Core 2 Quad Q6600 (3.6 GHz) based system.
However, there is a very logical explanation why the new AMD CPU didn’t impress us with its power consumption readings during overclocking. Even though Phenom II X4 processors use 45nm cores, they require much higher Vcore than Intel processors.