Investigating Intel's Lynnfield mysteries

I have a few questions to ask at this week's Intel Developer Forum....

Why is Intel using a more expensive chip for the new Core i5 and cheaper Core i7 processors? Why does this new chip--code-named Lynnfield--appear to have features Intel isn't using? What's the connection between Lynnfield and a future Intel chip code-named Jasper Forest?

These questions arose as I've been getting ready for IDF by reviewing recent press releases and news stories about Intel's current and forthcoming products, and chatting with fellow analysts about what we're looking forward to seeing there.

The recent announcements of the Core i5 and new Core i7 processors seemed pretty straightforward. Consider Brooke Crothers' piece on CNET: "Out with the old: Intel makes Core 'i' chips cheap." As Crothers explains, the facts are simple: the new Core i7 800-series slots in under the existing 900-series and replaces some older parts. The Core i5 is a new line, clearly positioned below the Core i7. Features, performance, and prices are all lower. That's as it should be.

But in looking at the coverage on some enthusiast sites, a fact jumped out at me. The Lynnfield chip is 12.5 percent larger than the Bloomfield chip used in the higher-priced Core i7 900-series processors (296 square mm vs. 263 square mm), in spite of the fact that Lynnfield only has two memory interfaces and no QuickPath Interconnect (QPI) link.

The big difference between the chips is the addition of 16 lanes of PCI Express on Lynnfield, but that's only about 80 pins plus the control logic. The changes should have roughly canceled each other out. Maybe one chip would be a little bigger than the other, but not by this much.… Read more