February 25, 2008 10:30 AM PST

Intel's Dunnington: Six cores on one chip

Posted by Tom Krazit

After months of deriding rival Advanced Micro Devices' strategy of cramming four cores onto one chip, Intel is set to take that concept a step further.

A leaked presentation authored by Sun has shed some light on Intel's plans for its Dunnington processor, which appears to be a six-core server chip where all six cores are part of a single chip. Intel had previously hinted that Dunnington would have four cores or more, but it hadn't been clear whether the company would reuse its multichip module strategy of cramming several distinct chips into a single package.

Sources familiar with Dunnington's design confirmed the presentation is accurate, and that the processor features all six cores on a single chip. The presentation also reiterates Intel's plans to release the Nehalem generation of chips with an integrated memory controller and point-to-point interconnects between cores later this year, borrowing design techniques from AMD's Opteron chips. Nick Knupffer, an Intel spokesman, declined to comment on Dunnington but said of Nehalem, "Nehalem is on track and a screamer, but we're not going to comment further."

This slide from a leaked Sun presentation uncovers Intel's six-core Dunnington processor.

(Credit: aceshardware.freeforums.org)

Dunnington would be Intel's first monolithic design since its original Core 2 Duo chips released in 2006. The presentation indicates that Dunnington has six 45-nanometer Penryn-class cores integrated onto a single die. Each pair of Penryn cores shares 3MBs of Level 2 cache, and each of the six cores can access 16MBs of Level 3 cache. That's a ton of space to store frequently used instructions, which could be a help for the chip in avoiding the front-side bus bottleneck to the main memory that's still apparently in the works for Dunnington.

Intel chose to build quad-core chips by taking two dual-core chips and putting them into a special package. This approach was scorned by the chip design purists, but it allowed Intel to get quad-core chips out quickly while AMD struggled for a year with the technical challenges associated with building Barcelona, a quad-core chip with all the cores on one die.

Dunnington will arrive just before the Nehalem generation of chips, which will be quite a mishmash of designs. Intel will have a wide variety of Nehalem chips, including ones with two, four, and eight cores, chips with up to 16 threads, and some with integrated graphics.