Cinebench rendering
We can take a closer look at power consumption and energy-efficient performance by using a test whose time to completion varies with performance. In this case, we're using Cinebench, a 3D rendering benchmark based on Maxon's Cinema 4D rendering engine.

This is a very different sort of application, in which the Shanghai Opterons' larger cache and faster memory don't bring the sort of performance gains we saw in SPECjbb. Here, the Xeon E5450 is faster. In fact, the Xeons are faster clock for clock—the Xeon L5430 at 2.66GHz outperforms the Opteron 2384 at 2.7GHz.

As we did with SPECjbb, we measured power draw at the wall socket for each of our test systems across a set time period, during which we ran Cinebench's multithreaded rendering test.

Some of the outcomes are obvious immediately, like the fact that the Xeon E5450 and X5492 systems have much higher overall power draw. Still, we can quantify these things with more precision. We'll start with a look at idle power, taken from the trailing edge of our test period, after all CPUs have completed the render.

The Opteron 2384 system's idle power draw is just over 10W less than that of the system based on its 65nm predecessor, the 2356, in spite of the fact that its L3 cache is larger and runs at a higher clock speed. Shanghai's ability to flush its L1 and L2 caches into the L3 and shut down its cores does appear to pay dividends. Even so, those incremental gains seem small in light of the considerably higher idle power draw of the FB-DIMM-equipped Xeon systems.

Meanwhile, the low-voltage Xeons and San Clemente continue to impress.

Next, we can look at peak power draw by taking an average from the ten-second span from 15 to 25 seconds into our test period, during which the processors were rendering.

Peak power draw with Cinebench isn't quite as high as it is with SPECjbb, but the trends remain the same. The Shanghai Opterons draw less power, at a higher clock speed, than their 65nm counterparts.

Another way to gauge power efficiency is to look at total energy use over our time span. This method takes into account power use both during the render and during the idle time. We can express the result in terms of watt-seconds, also known as joules.

We can quantify efficiency even better by considering specifically the amount of energy used to render the scene. Since the different systems completed the render at different speeds, we've isolated the render period for each system. We've then computed the amount of energy used by each system to render the scene. This method should account for both power use and, to some degree, performance, because shorter render times may lead to less energy consumption.

Even though the Opteron 2384 isn't as fast as the Xeon E5450 in this application, the Opteron system still requires less energy to render the scene than the Xeon E5450-based one. The Opteron 2356 isn't nearly as efficient as either, but the Shanghai Opterons more than restore AMD's competitiveness in power-efficient performance.

With that said, the biggest winner here, obviously, is the Xeon L5430 system, which is simply in a class by itself.