Sandy Bridge-E: Core i7-3960X Is Fast, But Is It Any More Efficient?

Sandy Bridge-E: Could The -E Stand For Efficiency?

Intel's Sandy Bridge-E design takes the company's 32 nm Sandy Bridge architecture to the next level. As you likely saw in Chris Angelini’s full review on Sandy Bridge-E And X79 Express, the new high-end processor family offers more of almost everything: more cores, more cache, more memory channels, and more PCI Express connectivity, resulting in better benchmark scores in almost every discipline.

While the new processor design, which is now available as the Core i7-3960X and Core i7-3930K (and Core i7-3820 some time next year) delivers more performance, we've already seen the first review machines based on X79 Express lowering power consumption versus the Gulftown/X58 combination thanks to the dual-chip platform layout. AMD might not want to learn in detail what this could mean in terms of performance per watt, since the six-core Core i7-990X was already faster than its flagship FX-8150.

The Numbers Game

The secret sauce of Sandy Bridge-E turns into a relatively simple recipe, which reads: do more of the same. This is made possible by the solid performance per core of Sandy Bridge, and the parallelism of a six-core implementation. In other words, it appears that Sandy Bridge scales very well, so it makes sense that Intel would introduce it as a six-core desktop offering and, later, an eight-core server-oriented Xeon processor.

In short, Sandy Bridge-E facilitates up to six cores (rather than the four you max out with on LGA 1155), includes four 64-bit memory channels (rather than LGA 1366's maximum of three), boasts official memory data rates as high as 1600 MT/s, and features 40 PCI Express 3.0-capable lanes. Moreover, the 2.27 billion-transistor processor occupies 434 mm² of die space, too.

Getting Rid Of Dead Weight

But Sandy Bridge-E also sheds certain elements that might otherwise contribute to its overall power consumption. As on Sandy Bridge, power gating allows unused parts of the processor to be almost completely shut down, minimizing power consumption. Add that to the single-chip platform, which replaces its predecessor's two-chip layout, and you have the foundation for new lows in idle and peak power usage compared to any other six-core CPU in the lab.

The promise, then, is one of new efficiency records, particularly in applications able to leverage Sandy Bridge-E's parallelism. Just recently, we looked at the performance per Watt of AMD’s FX processor in the article AMD FX: Energy Efficiency Compared To Eight Other CPUs. In today’s article, we’re performing the very same experiment.

So, if you’re in search of information on power efficiency, have a look at the aforementioned story. Or, if it's architectural details you're after, make sure you've already read our Sandy Bridge-E launch article for more the story about design and performance.

Sporting six cores, 32 nm lithography, 15 MB of shared L3 cache, and clock rates between 3.3 and 3.9 GHz, depending on workload, is the Core i7-3960X a good foundation on which to enable great power efficiency? It seems like it could be, as the idle power consumption of 87 W measured in our launch coverage represents a record low for a high-end desktop PC.