Intel Core i7-980X Gulftown Six-Core 32nm Processor Review

Westmere Microarchitecture - Gulftown Edition

In 2007, Intel unveiled the Tick-Tock Model as a demonstration of the company's dedication towards continued rapid technological innovation. The "tick" is a shrinking of the previous architecture manufacturing process (65nm --> 45nm --> 32nm) and the "tock" is a new architecture. First launched in November 2008 with the Bloomfield Core i7-900 series, the Nehalem microarchitecture saw its second variant launched in September 2009; the Lynnfield Core i5-700 series & i7-800 series. Lynnfield was nothing radically new, it merely used Nehalem's modular design to integrate the PCI-Express controller into the CPU die.

In January 2010, the "tick" to 2008's "tock" appeared in the form of the Clarkdale, the first Westmere-based processors. Westmere shrinks the Nehalem architecture down to 32nm, which is a 41% smaller manufacturing process than 45nm. This is important because manufacturing cores on a smaller process allows for cooler running chips, better power efficiency, higher frequency scaling, and perhaps most importantly more cores on a CPU package, which is what Gulftown is all about.



There is no way around it, fundamentally speaking Gulftown is basically just a six-core Bloomfield with an extra 4MB of L3 cache and manufactured on Intel's ultra-modern 32nm high-k+ metal gate transistor technology. Obviously, it doesn't have Lynnfield's integrated PCI-Express controller and it doesn't have an integrated GPU like Clarkdale does. We will have to wait for Sandy Bridge to see both those features built into a hexa-core processor. Frankly though, those are two elements we can live without, since the X58 IOH is more than capable of handling PCI-E duty and there's no place for an IGP on a high-performance platform.

In quantifiable terms, Gulftown's CPU die size is 248mm². By comparison, Lynnfield comes in at 296mm² and Bloomfield measures 263mm². Thanks to the 32nm process Intel have managed to stuff 50% more cores and cache, yet reduce the overall die size by about 6%. Transistor-wise, this is the first consumer-oriented processor to break the 1 billion mark. The Gulftown CPU die is packed with 1.17 billion transistors. This is healthy increase from Lynnfield's 774 million transistors and Bloomfield's 731 million transistors. On an interesting sidenote, AMD's 'Istanbul' six-core Opteron processors, which are manufactured on a 45nm process, have 904 million transistors and a whopping 346mm² die size.

Now many of you are probably looking at the die pictures and saying "It is pretty but what am I looking at exactly?". A valid question, so let's take a look at the Gulftown CPU core layout:


Anyone familiar with Bloomfield's die layout will see nothing but similarity with Gulftown, and this is because of how the Nehalem microarchitecture was designed. Which leads us to...


Part of the reason that Intel is able to add and remove parts so easily is because the Nehalem architecture is dynamically scalable, and it was designed with modularity in mind. What this means is that Intel can custom create processors based on the needs of the market without having to go design a brand new chip from scratch. They can add or remove cores, L3 cache, memory channels, memory controllers, power management features, and even integrated graphics. Therefore, Intel have the ability to add new blocks to the core without having to go to the drawing board and redesigning the whole layout. Basically, they are only limited by how much stuff they can actually fit on one CPU package. Think of it as a multi-million dollar Lego set.


If you are unfamiliar with the features and technology present in Nehalem-based processors, or simply want a more in-depth explanation as to what Intel have added/tweaked on Gulftown, the following section should interest you.