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Intel Westmere Architecture and Clarkdale Processor Preview

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Subject: Processors
Manufacturer: Intel
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Clarkdale makes its debut

Last week while attending the annual Intel Developer Forum, we sat down with Intel's technical marketing and benchmarking team to discuss an upcoming product line you will be seeing LATE in 2009 or possibly early in 2010.   These will be based on the 32nm process technology and the upcoming Westmere core which will both puts the Nehalem architecture through a die-shrink and enables it to enter an even lower cost market. 

For a quick rundown of the below content, check out our video coverage here:

Now, for a bit more detail, better diagrams and opinion, keep reading below about those upcoming Clarkdale and Arrandale CPUs.

Though a bit vague with the "2009+" moniker here, Intel essentially has two products based on the Westmere core coming out late in the year: Clarkdale and Arrandale.  Both are essentially identical though the Clarkdale parts are aimed at the desktop while Arrandale will find a home in the mobile space. 

You can see here that Westmere will only be a dual-core product though HyperThreading will be enabled across the core to support a total of 4 threads.  While disappointing for some enthusiasts, dual-core quad-threaded processors should be more than enough for the target audience here and in order to facilitate inclusion of other new features, it was required. 

Westmere looks very similar to Lynnfield, though of course with two cores instead of four.  There are some key changes though: integrated graphics is included on the CPU package (not on die) and the IMC (integrated memory controller) has actually been moved off the CPU die and into the other die.  It is still dual-channel DDR3 also.

The chipset solution is basically the same as the P55, though we are getting a new offering, the P57.  The only change here is that the chipset has a display interface for the processor to use with its integrated graphics to facilitate video outputs.  This connection is pretty low bandwidth but will be another physical connection for the board vendors to run traces for on P57 offerings. 

The P57 chipset improves on the integrated audio as well by supporting true uncompressed digital audio formats and new Blu-ray audio codecs like Dolby TrueHD.  We saw this working in the demo booth with a copy of Madagascar using a high quality audio receiver.  It is nice to see companies like Intel taking this audio issue a bit more seriously than they had before on the G45 platform.

Though this image is of Arrandale, Clarksdale is built in an identical fashion.  There are two physical dies on the same CPU package.  The smaller die is built on the 32nm process and includes only the dual-core processor cores.  The larger die is still going to be built on the 45nm process and will including the integrated graphics cores as well as the integrated memory controller.

You are likely asking yourself why Intel bothered to move the memory controller from the CPU die to the external die.  While Intel wasn't completely open we are pretty sure there were some issues moving the IMC from the 45nm process to the 32nm process
and simply keeping it at 45nm was an easy solution.  It could also be that the GPU on die would benefit more from the slightly lower latency than the CPU cores would. 

The GPU on the Westmere core does see a slightly upgrade from the G45 products it is based on.  There is a bump from 10 shaders to 12 SPs and general improvements have been made all around.  Don't expect performance to be rivaling AMD or NVIDIA based IGP solutions but it should at least be better.

Of course, the P57-platform and Clarkdale processors will still support discrete graphics via a PCI Express 2.0 interface if the user wants to add-in the extra card.

The Clarkdale CPUs will continue to use the new LGA1156 socket that launched with the P55/Lynnfield CPUs this month and in fact these new CPUs SHOULD work in any existing P55 motherboard.  The only drawback of course is that the integrated graphics would NOT function on a P55-based motherboard and in reality, any Lynnfield CPU you could already own will be faster than Clarkdale when it is released. 

The Westmere core also adds a significant new feature that accelerates AES encryption and decryption for file and whole-disk security.  This basically allows the CPU to do 128-bit decryption in real-time so securing your files on your PC will have little to no effect on system performance. 

Both Clarkdale and Arrandale (the mobile variant) will have support for Turbo Mode for the CPU cores but the Arrandale offering will also include an interesting twist on the technology, integrating the GPU in the mix.  With a fixed TDP, the processor will either accelerate the GPU or CPU cores depending on the work load - while gaming the GPU will able to "steal" some of the overall TDP to increase its clock speed and vice-versa.  This is a very elegant solution that could go a long way towards improving overall battery life in mobile computing.

As for Clarkdale, because it will always be plugged into the wall, the GPU will apparently always be running at full speed.

Here you can see a mini-ITX reference board for the new Clarkdale platform.  The two-chip solution does allow the board to have a much cleaner design than previous solutions using the Core 2 CPU, P45 chipset and ICH9 south bridge.  All on this one tiny motherboard you will see DVI and HDMI output, eSATA, 8-channel analog and digital audio output, the LGA1156 processor socket, a single PCIe x16 slot for graphics expansion, two DDR3 memory slots and more.

You may also see a black socket right behind the DVI port and wonder what that is: it was meant to house the upcoming Braidwood cards but since that technology has been pushed back, you will not be seeing that connection on the board when it ships.

One very cool demo that Intel was showing was a power consumption comparison between a Clarkdale system and the monitor being used for output.  Can you guess which is using less power and idle?  The mini-ITX motherboard with a Clarkdale CPU was only using 24 watts or so at idle while the monitor was pushing 40 watts. 

Even when pushing a four-thread run of CineBench 10, the Clarkdale system used about 70 watts of power.  Very impressive!

Now let's take a look at some performance numbers; keep in mind that these were run by Intel, not by us, so take them with a grain of salt.  They are normalized to a Core 2 Duo E8500 processor that runs at 3.16 GHz.  The Intel Clarkdale processor is running at 3.33 GHz.

Here are some quick results from the popular SPEC*int tests that show the Clarkdale processors, even as a dual-core CPU with HyperThreading technology, are able to meet or beat the quad-core Core 2 Q9400.

The 3DMark Vantage results show another big win in both the CPU and graphics tests indicating that the CPU and updated integrated graphics are pulling their weight.

The SiSoft Sandra results show impressive memory bandwidth improvements over the Core 2 parts with the memory controller on the P45 chipset.

Finally, looking at PCMark Vantage, we find that the Clarkdale processor will offer about 43% better performance than your standard Core 2 Duo CPU available today.

Closing Thoughts

Westmere won't excite everyone but the prospect getting significantly better performance than dual-core and quad-core Core 2 processors available today while using much less power at idle and load while introducing new features like AES encryption acceleration and on-CPU graphics should getting your gears working.  Home theater PCs will definitely look more and more enticing with 24 watt idle power consumptions and support for the best quality audio and video formats/codecs right out of the box. 

There is a bit of confusion from a lot of readers about Clarkdale and Arrandale though about why the company would only introduce dual-core variants and seemingly leave quad-core processors to Lynnfield for most of 2010.  Intel answers that Gulftown will be out for the enthusiast pretty soon (6-core LGA1366 part) but that will only appeal to a select few users.  In reality Intel likely could not fit both a quad-core CPU and integrated graphics with IMC on the same package and thus cutting the cores down to a pair was required. 

Also, why would Intel move the integrated memory controller off the CPU die for only a generation when they are already planning on integrating all of the components (CPU, GPU and IMC) into a single die with Sandy Bridge?  That is something we hope to get answered very soon but for this level of CPU performance the memory controller movement will likely not affect performance more than a couple of percent, even in the worst case.

So while not everyone is going to be excited about Clarkdale and Arrandale, we definitely are.  The world of notebooks should benefit significantly in terms of performance/watt (and leave those Clarksfield notebooks where they belong, on the shelves).  Budget PCs will also enjoy a nice feature and performance boost.  If prices are as low as expected, Clarkdale will surely find a home in many a desktop this winter.

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