A CPU Paradigm Shift

Tonight Intel has pulled off the wraps on their new Sandy Bridge microarchitecture. The fact that they did so a few days ahead of schedule should tell you just how confident they are in what is the biggest CPU architecture change since the Pentium 4.

Officially branded “2nd Generation Core Processor Family”, SB follows Intel’s strict “Tick, Tock” design philosophy, where they alternate between microarchitecture changes, and die shrinks.

The leap from Nehalem to Sandy Bridge is a much bigger gap than we’ve previously seen however, as Intel have made major changes in just about every component that comprises a microprocessor. We are not going to go into every detail of these changes, as that particular information has been out for a while. What I will say is that every single change made to the design of the chip is meant to facilitate faster execution of concurrent data. The Out of Order Execution Engine in particular has been revamped, and the CPU does a better job of prediction than ever before.

Looking at the CPU itself, it looks similar to those we’ve seen recently from Intel. Four cores exist on the die with a shared L3 cache, alongside a dual-channel DDR3 memory controller. A striking difference though, is the GPU sitting right there next to the CPU cores. Intel has had GPUs and CPUs coexisting with Clarkdale, but in that case, the GPU was a on separate die that sat next to the CPU and communicated over an MCP interface.

This time, the GPU is right there on the same silicon, and has been completely revamped. It is the most powerful integrated GPU to date (although that is speaking relatively, of course), and has a host of new hardware video decoding and encoding features.

Another area of focus was power efficiency. Sandy Bridge is designed from the ground-up to be as energy-efficient as possible, without sacrificing speed. Along with designing the silicon to be more efficient than Nehalem, Intel has tweaked the way Turbo Boost works. The new version of Turbo Boost has a sort of “super boost” function, that pushes the CPU beyond its TDP rating when possible. For instance, if you have loaded an app like Photoshop CS5 or Excel 2010, it probably takes more than a few seconds even on a high end chip. The new Turbo Boost will ramp up the CPU higher during times like these, and it will do so more quickly.

This feature, along with the overall vastly improved design of Sandy Bridge makes overall desktop usage noticeably faster compared to every other chip I’ve ever used (and I already said that when Nehalem came out, so you can imagine how it feels now).