Intel Core i3 and Core i5 661 (Westmere)
4th Jan 2010 | 11:30
Intel's new budget chip brings 32nm transistors and CPU-GPU fusion tech
Intel Core i3: Overview
Tick-tock goes the Intel PC processor clock. "Tick-Tock", of course, is Intel's slightly poncey parlance for a strategy of introducing new chip production technology and CPU architectures on alternate years.
This time around, Intel is treating us to a 'tick'. That means a shrink from 45nm to even tinier 32nm transistors, rather than a radical new CPU architecture.
In other words, Intel's new Core i3 500 series and Core i5 600 series processors, launched today, are derived from the existing Nehalem processor design. They're not all-new chips.
At least, the traditional CPU part of this new 32nm family of processors, known internally at Intel as Westmere, isn't new. What is novel is the shoehorning of graphics rendering hardware into the processor package.
That's right, these Core i3 and Core i5 chips are the first examples of the coming era of CPU-GPU fusion chips from both Intel and its main rival in the PC processor business, AMD.
Intel is also launching a mobile version of this all-in-one processor design for laptops. You can read our full, exclusive review of that very soon.
Intel Core i3: Technical details
Despite the doubled up i3 and i5 branding (more on that in a moment), the 32nm Westmere desktop processors released today are all essentially the same underlying chip, known as Clarkdale.
In CPU terms, it's a low end dual-core offering.
But by virtue of being the first significant PC processor with graphics processing integrated into the CPU package itself, it is nevertheless an extremely important chip.
Indeed, for many PC enthusiasts, the very idea of a CPU-GPU fusion processor is something of an abomination, an unholy alliance that bodes ill for performance.
Whatever the merits, the industry as a whole is adopting an increasingly prophetical tone when discussing fusion processors. Forgive us a Battlestar Galactica-ism, but as Gaius Baltar would say, Clarkdale is the shape of things to come.
Chip off the old block
But is it worthy of BSG's portentous orchestral movements? Well, one thing Westmere isn't, funnily enough, is a single chip. In fact, it's two squeezed into a single processor package.
The first chip, packing two processor cores and cache memory, is fabricated courtesy of Intel's brand spanking new 32nm tech. However, the second, which contains the memory controller, system I/O and that all-important integrated graphics core, defaults to the relatively old school 45nm node.
If that strikes you as something of a hodge-podge of silicon bits, you're on to something. Intel's original plan was almost definitely to put the whole shebang on 32nm. Ultimately, it was decided that attempting a first CPU-GPU fusion chip on a brand new production process was probably asking too much.
A 'true' single-chip fusion processor from Intel will therefore not appear until the end of 2010 and the debut of the new Sandy Bridge architecture - assuming that arrives on time.
If all that isn't complicated enough, with Clarkdale, Intel continues to insult our sense of logic with its branding strategy. This new processor will be sold as both a Core i3 and a Core i5.
In a way, it makes sense. After all, Intel sells the quad-core Lynnfield processor as both Core i5 and Core i7. But the distinction there was the presence of HyperThreading technology. With Westmere, it's actually Intel's auto-overclocking Turbo Boost feature that makes the difference. Core i5 chips get it, Core i3 chips do not.
The upshot of all this is that consumers will be largely clueless regards the several seriously important differences between the various architectures that underpin the full range of Core i3, i5 and i7 chips.
Unless, that is, they bone up on the the triple digit suffix Intel adds to the branding, for example Core i5 661. And that's not going to happen. So clueless they will remain.
Intel Core i3: Performance
Anyhoo, a broad range of Westmere-based Core i3 and Core i5 chips is available from today, ranging from the 2.93GHz Core i3 530 up to the 3.46GHz Core i5 670.
All are dual-core CPUs with 4MB of on-die cache, a dual-channel DDR3 memory controller and that integrated graphics core.
Nothing to do with Larrabee
As for the latter, don't get too excited. It's a close relation to Intel's existing and underwhelming integrated motherboard GPUs.
It gets an extra pair of shaders to give a grand total of 12, along with higher clocks and improved video decode support. That decode performance will be handy for laptop variations on the Westmere theme (review coming soon), but fundamentally, it's not a new graphics design.
For the record, it's also worth noting that the presence of graphics in Clarkdale CPUs means a new motherboard is required.
While the existing LGA1,156 socket interface is retained, routing and outputs for the graphics are needed. They're provided by the new Intel 57 series chipset.
All of which brings us to the minor matter of how this new budget Intel beastie performs. Our main focus for testing is the Core i5 661, officially a 3.33GHz model with purported Turbo frequencies up to 3.6GHz. However, we'll also be able to draw conclusions about the pace of cheaper Core i3 models.
Overall, our initial impressions are mixed. The good news is that raw CPU performance is immense for a dual-core processor. In fact, the dual-core i5 661 delivers comparable performance to a quad-core chip from Intel's older Core 2 family of processors.
Core i3 models such as the 2.93GHz 530 and 3.06GHz 540 will only be slightly behind.
Doubts creep in
The performance of the integrated graphics isn't too hideous, either. It's approximately on a par with the previous generation of competing motherboard-based solutions from the likes of AMD and Nvidia. That actually represents an improvement for Intel.
Where doubts creep in, however, regards the thermal implications of housing both graphics and CPU in a single package. The 661 has little stomach for overclocking. More worryingly, it refuses to hit Intel's claimed 3.6GHz in turbo mode. 3.45GHz is as good as we got.
As a solution for cheap and cheerful computing, such considerations carry little weight. But it does give the impression of an architecture running close to its design limits. Likewise, there's plenty to turn off PC enthusiasts looking for a cut-price route to high performance.
We are not, therefore, overly enamoured by Westmere as a desktop chip. For now, there are too many drawbacks and too few advantages (read none) with the CPU-GPU fusion design for the desktop.
In laptop PCs, however, things could be different. To find out more about the impact Westmere has on Intel's new mobile platform, check back soon for our exclusive review.