There has been a lot of talk in the investment community regarding the transistor density of Intel(NASDAQ:INTC) 14-nanometer technology. Intel says its 14-nanometer technology is inherently denser -- that is, more transistors can be packed into a given area -- than competing 14/16-nanometer technologies.
Interestingly though, Intel released some transistor counts and die areas of a couple of its 14-nanometer chips -- namely the 2+2 and 2+3 configurations of its Broadwell-U processors for low-power notebooks. The densities of these chips were about twice those of the 22-nanometer Haswell-U processors, but they were not as dense as, say, the Apple A8X built on Taiwan Semiconductor's 20-nanometer process.
It is well known that the density of a chip depends on the design goals for said chip. For example, at the Intel Developer Forum last year, Intel process technology guru Mark Bohr shared the following slide:
The purpose of this slide was to illustrate that chip designers could use different interconnect stacks -- which play a key role in determining the performance and density of a chip -- to optimize for different things such as cost, density, and/or performance.
A real-world example
I would like to provide a "real-world" example of what Intel talked about in the slide. In particular, I would like to compare the densities of two products, both built on Intel 14-nanometer technology with vastly different transistor densities.
According to Intel, the Broadwell-U 2+3 configuration features 1.9 billion transistors and fits into an area of 133 square millimeters. This implies a density of approximately 14.3 million transistors per millimeter squared.
Now, take the recently released Intel Xeon D -- a highly integrated system-on-chip aimed at low-power servers. SemiAccurate reported that the Xeon D die weighs in at 160 square millimeters. Intel, in a recent post on Twitter, said its Xeon D processor is made up of 4.3 billion transistors -- implying a transistor density of approximately 26.88 million transistors per square millimeter.
That is nearly twice the density observed in the aforementioned Broadwell-U processor.
What is going on here?
If we work under the assumption that the transistor counts in both chips are apples to apples, then the question is: What is going on?
One thing to keep in mind is that Xeon D features eight CPU cores, 24 PCI Express lanes, and two integrated 10-gigabit Ethernet connections. That main complex also features 8 megabytes of L3 cache. The chip does not feature integrated graphics.
The CPU cores run at a base clock of 2.00GHz and can turbo up to a maximum of 2.6GHz, while the Broadwell CPU cores can turbo to up to 3.4GHz -- a 30% difference.
My guess: More of the Xeon D die is made up of cache memory, which is known to be denser than logic, helping chip density. Intel may also be using high density.
Furthermore, I suspect that the Xeon D is built using a metal stack optimized for density rather than for high frequencies (hence the max turbo of just 2.6GHz) to be able to integrate as much as possible into a relatively small footprint.
I would bet you Cherry Trail is even denser
Intel has not released the transistor count for its low-power 14-nanometer Atom processor known as Cherry Trail. This is probably the closest we would be able to get to an apples-to-apples comparison with a system-on-a-chip such as the Apple A8.
Given Intel's reluctance to talk about die sizes and transistor counts with respect to its Atom processors, I am not going to hold my breath for more detailed disclosures.
Ashraf Eassa owns shares of Intel. The Motley Fool recommends Apple and Intel. The Motley Fool owns shares of Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.