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Sandy Bridge: full technical details

Posted on 13 Sep 2010 at 23:56

The low-down on Intel's newest and most powerful CPU architecture

Intel has revealed extensive technical details of its new Sandy Bridge architecture, unveiled today for the first time at the Intel Developer Forum in San Francisco.

The new platform is, in Intel’s parlance, a “tock” – a major new design based on an existing manufacturing process, in this case, the 32nm high-κ metal gate process introduced last year in the Westmere architecture. So, as you’d expect, it brings several major changes from what’s gone before.

On-die graphics

Sandy Bridge is Intel’s first architecture to integrate the GPU onto the same silicon die as the CPU (in Westmere the two were on separate dies inside the processor package). This enables the two components to share on-chip cache memory, which is more power efficient than using system RAM and significantly faster: Intel claims a four-fold improvement in bandwidth.

Sandy Bridge is Intel’s first architecture to integrate the GPU onto the same silicon die as the CPU

The GPU hardware has also been upgraded from the HD Graphics found in Westmere CPUs. Operations commonly involved in media playback and encoding, such as texture sampling and colour blending, are now handled by dedicated units, saving power by reducing reliance on comparatively heavyweight shader units.

And more complex tasks – those that do require shader power – benefit too, as the graphics register space has been expanded and performance for some types of operation has been improved. Here, Intel hasn’t given any benchmarks, but Intel Fellow Tom Piazza has indicated that the new graphics core should be a significant step up from Westmere.

Components and connectors

Sandy Bridge retains the integrated PCI Express controller found in Nehalem and Westmere, and adds an on-chip DisplayPort controller.

All Sandy Bridge designs also incorporate a dual-channel DDR3 controller, suggesting that the triple-channel system used by the LGA 1366 platform is being sidelined.

“We’ve found a very high percentage of clients will only tolerate two memory channels,” explained Opher Kahn, senior principal engineer for Sandy Bridge. “OEMs wanting to build for three channels need to use chips that aren’t based on this design. It’s a small market that we’re not going to separate out of this chip design.”

It’s been widely reported that Sandy Bridge will use a new LGA 1155 socket, but Intel hasn’t officially confirmed this. Nor, at the time of writing, has Intel confirmed or denied rumours reported last week that Sandy Bridge will bring with it a new south bridge that includes native support for USB 3.

In fact, prototype Sandy Bridge motherboards on display at IDF have had their sockets covered up, and no blue USB ports have been spotted.

Core refinements

Sandy Bridge is Intel’s first processor to support AVX (advanced vector extensions), a new set of processor extensions that increase performance in the type of parallel, repetitive operations frequently used by media applications.

Kick-down automatically provides a brief but aggressive frequency boost when user activity is detected

Demonstrations at the opening keynote showed a Sandy Bridge system performing HDR photo processing and 3D rendering almost twice as quickly as a Core i7, though the precise specifications of the two systems weren’t revealed.

Performance is further enhanced by an upgraded version of Turbo Boost, which can now ramp up core speeds to a degree that actually exceeds the system’s nominal TDP (thermal design power) – so long as overall thermal conditions permit it. And a complementary system, informally called “kick-down”, automatically provides a brief but aggressive frequency boost when user activity is detected, to maximise responsiveness for interactive tasks.