CES 2011: A closer look at Intel's Sandy Bridge chips

Intel will announce its new line of processors, code-named Sandy Bridge, at a press conference tomorrow, but at this point it is a mere formality. The changes to the microarchitecture have been known for some time and the only remaining question was just how well Sandy Bridge would perform. Now we now that too.
Written by John Morris, Contributor

Intel will announce its new line of processors, code-named Sandy Bridge, at a press conference tomorrow but at this point it is a mere formality. Most of the major changes to the microarchitecture have been known since the Intel Developer Forum last September. The only remaining question was just how well they would perform, and with numerous hardware enthusiast sites posting test results this week that question has largely been answered as well (more on that below).

My colleague, Sean Portnoy, covered the news in an earlier post. But here's a closer look at some of the new features of Sandy Bridge and how they affect performance.

Intel is expected to announce a total of 29 Sandy Bridge processors for laptops and desktops, as well as 10 supporting chipsets and four wireless options. The mobile processors include 10 standard voltage chips and five low-voltage parts for ultra-thin models. The standard voltage processors will range from the 2.10GHz Core i3-2310M dual-core all the way to the $1,096 2.50GHz Core i7-2920XM Extreme Edition. The Core i3-2310M and three others are "transactional SKUs" meaning Intel sells them directly to computer companies only and not as boxed upgrades in retail, and therefore doesn't disclose pricing. But the mid-range Core i5-2520M dual-core will sell for $225, so it seems likely that some of these first Sandy Bridge mobile CPUs will be priced at less than $200. (These transactional processors also lack a few features such as Intel vPro, Trusted Execution Technology, and the new instructions that speed up data encryption.) The desktop processors will include eight standard chips and six versions for small-form factor desktops and home-theater PCs. The standard desktop processors range from the $117 3.1GHz Core i3-2100 dual-core to the $317 3.4GHz Core i7-2600K quad-core.

The base frequencies are only half the story. The Turbo Boost frequencies of the CPU cores as well as the dynamic frequency of the graphics processor vary depending on the processor and price. This isn't really new, but with Sandy Bridge Intel has even more knobs to turn here to address different prices and segments. The handful of processors with a "K" designation are unlocked, meaning it is easier to overclock them to even higher frequencies for maximum performance, though only enthusiasts use this feature. The unlocked 3.1GHz Core i5-2600K quad-core chip, at $216, is likely to be a popular choice for this crowd.

With the exception of Atom-based netbooks, the Sandy Bridge mobile processors will take over the entire range of Intel laptop mobile processors throughout 2011. The dual-cores will replace the 32nm Arrandale dual-cores in mainstream laptops and the quad-cores will replace the older 45nm Clarksfield quad-cores. The desktop picture is a little muddier. Sandy Bridge dual- and quad-core processors will replace the Clarkdale dual-core processors in budget and mainstream desktops. Some performance desktops will also use Sandy Bridge, but Intel expects to continue to sell the older Lynnfield 45nm quad-cores, such as the Core i7-875K, and at the very high-end the Gulftown six-cores, such as the Core i7-980X, through 2011 as well.

Sandy Bridge isn't a "shrink" to a more advanced node. It uses the same 32nm process technology as the Westmere processors that Intel introduced at CES a year ago. In Intel's parlance, Westmere was a "tick" and Sandy Bridge is a "tock." But don't let that fool you. Sandy Bridge introduces a new design that is a significant departure from current Intel processors. Ivy Bridge, the 22nm processors that Intel is scheduled to release in early 2012, will also be based on this new microarchitecture.

The most visible change is a higher level of integration. Like Westmere, Sandy Bridge has an integrated memory controller and PCI-Express 2.0 links, but the new microarchitecture also includes Intel's HD Graphics on the same 32nm die (Westmere has a 45nm graphics processor in the same package, but not on the same slice of silicon). There are two versions of the new graphics: the HD 2000 with six execution units (EUs) in low-end desktop chips and the HD 3000 with 12 EUs in the mobile processors and other desktop parts. The result is a processor with a transistor count that is reportedly just shy of a billion for the quad-core versions.

But there are other changes too including a special cache for decoded micro-operations; improved out-of-order execution; and a high-bandwidth ring bus that connects the CPU cores, last-level cache and graphics. Each core has a new floating-point unit that supports new AVX (Advanced Vector Extensions) instructions for processing vectors up to 256 bits in width for better performance on floating point-intensive applications. The integration of the CPU cores and graphics in a single chip also lets Intel fine-tune performance and power depending on the application. The enhanced Turbo mode can easily push a single CPU core to 4GHz or faster on applications that do not benefit from multi-threading. Finally, Sandy Bridge adds dedicated hardware video playback and encoding, which results in some of the biggest performance improvements.

So just how fast is Sandy Bridge? The answer is complicated because there are so many different versions of Sandy Bridge competing across nearly all laptop and desktop segments. But all reviewers agree that Sandy Bridge processors are significantly faster than both the older 45nm quad-cores and the newer 32nm dual-cores, though not quite as fast as the Gulftown six-core chips, which start at nearly $900 and cater to a niche market. The Core i7 and Core i5 quad-cores are generally faster than AMD's Phenom II X6 six-cores and the Core i3 and i5 dual-cores rival AMD's similarly-priced Phenom II X4 quad-cores.

The graphics have also gotten a big boost. Serious gamers will still need discrete graphics from AMD or Nvidia, but it is now possible to play demanding 3D games with acceptable frame rates albeit at lower resolutions and quality settings. For casual gaming and Blu-ray video playback, there's no question it is more than capable. It looks like some of the biggest performance gains are in video encoding, especially with Intel's QuickSync hardware acceleration which also frees up the CPU for other tasks.

So far all of this looks pretty impressive. But what I'm most interested to see is what Sandy Bridge processors can do in real laptops. A few sites have posted tests results for Sandy Bridge quad-core mobile processors in "reference" desktop replacements, but this is easy stuff. I want to see what Sandy Bridge means for ultraportables with 12- and 13-inch displays--not only in terms of performance, but also battery life. With more than 500 laptop and desktop designs in the works, according to Intel, there should be plenty of Sandy Bridge-based PCs of all shapes and sizes to see at CES this week.

First Intel Sandy Bridge reviews:

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