Cool’N’Quiet 3.0 and Power Consumption
As we mentioned earlier, AMD has implemented Cool’N’Quiet 3.0 into Phenom II. These new power states and features combined with a significant die shrink to 45nm has put the Phenom II into a whole new arena. Although the overall TDP rating of the Phenom II X4 940 hasn’t decreased compared to the Phenom 9950, its clock speed has increased by 400MHz and its L3 cache is 3 times as large. Its operating voltage has also remained constant at 1.35V. Considering all of these boosts to the processor, we think that AMD’s 45nm immersion lithography has paid off quite a bit.
Before we delve into a pretty graph, we wanted to take a quick look at Cool’N’Quiet 3.0. One of the most significant features of CNC 3.0 is its three reduced frequency and voltage states. Cool’N’Quiet 2.0 was not quite as complex as it simply decreased the CPU multiplier along with the VCore when the processor was idle and shot it back to default when a load was realized. The problem with this is that a light load would trip the CPU back to maximum frequency when maximum frequency was not really necessary.
With Cool’N’Quiet 3.0, AMD has introduced an intermediate power state that kicks in with light loads and has further reduced the lowest state for even more power savings. The CPU has the ability switch between 800MHz, 1800MHz and 3000MHz frequencies and 1.0V, 1.15V and 1.35V respectively.
At its lowest power state, the Phenom II reduces to only 800MHz and a tad less than a volt. Previous Phenom processors dropped as low as 1000MHz, but never as low as the 4X CPU multiplier.
At the intermediate state, a 9X CPU multiplier is used for an 1800MHz core clock at 1.15V. This intermediate state kicks in when a light load is realized and helps to further reduce power consumption while having a negligible impact on performance. As soon as a heavy load is realized, the CPU immediately jumps to maximum frequency.
This sounds all fine and dandy in theory, but let’s see how AMD’s new 45nm Phenom II does in practice.
The Phenom II does not disappoint. Although its full load power consumption is the highest on our chart, it is only six watts higher than our 2.4GHz triple core. At idle, we see an entirely different picture. Put simply, the Phenom II is very energy efficient thanks to Cool’N’Quiet 3.0. It uses even less power at idle than the very energy efficient Phenom 9350e and a full 10 watts less than the Q6600 with C1E enabled.
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