The dark side of Westmere...

Now we're getting to the bad part of Clarkdale processors, which lies just across two CPU cores. Yes, I'm talking about the integrated graphics processor as Intel refers to it. To get a better idea what this chip is, think of the older G45 chipset used on LGA 775 motherboards. It's made in 45 nm, just like the one implemented on Clarkdale, it has the memory controller, a PCI-E bus controller and an integrated graphics processor. Now if you're thinking that's a lot of similarities to the chip that was implemented on Clarkdale, you'd be right on the money. Integrated graphics in Clarkdale is based on same design as the G45 chipsets with addition of two extra execution (shader) units. Both memory controller and PCI-E bus are implemented in the graphics die, and sadly, it's not the same memory controller used in Nehalem processors, rather a tweaked version of the one seen in P45/G45 chipsets with Core 2 processors. Although the memory performance is much improved over Core 2, memory latency will be a big limiting factor for new Clarkdale CPUs, as you will see from tests up ahead. It should also be mentioned that the memory controller supports up to dual-channel DDR3 at 1333 MHz.



A memory architecture optimized for Nehalem/Westmere will arrive next year with Sandy Bridge, along with a new IGP chip as well. Unlike Westmere, Sandy Bridge processors will not come in a MCM package, both IGP with PCI-E bus and IMC will be integrated onto a single die with the CPU cores. Until then, Westmere leaves a bad taste of beta test subject with a strange mix of old and new, good and bad...

Communication between the two chips (IGP and CPU cores) is done via QPI, while the motherboard chipset either P55 or H5x communicates with Clarkdale via older DMI. The graphics core on the other hand has another link to the outside world, called Flexible Display Interface or FDI. It's used to send the video signal to the I/O ports on the back of the motherboard, so if you are to make use of integrated graphics you must pair up Clarkdale with a H55 Express or H57 Express motherboard. Motherboards with P55 chipsets do not support FDI and your graphics core in the processor will just sit there unused, idling, wasting resources and producing heat. The most frustrating part is that the IGP supports power mangement to reduce heat and power output, but Intel enabled those features only for mobile platforms, so if you pair your Core i5 Clarkdale with a P55 motherboard the IGP will probably double the idle power consumption, not to mention add some extra heat waste.



But... there is a bright spot in this darkness and negativity. Look at the picture above and notice how the new platform with Westmere processors looks more much compact and cleaner related to the older LGA 775 Penryn based platform. All the important functions are now located in just one block (processor) while motherboard logic is left in charge with simpler functions like storage and handling input/output device streams. This picture can be taken as a hint to what Intel plans to do with these new processors and where the future of computing is probably heading. Small, compact, quiet platforms, yet powerful enough to satisfy the needs of most users. The true power of Westmere and for that matter future Sandy Bridge processors lies in portable and small form factor computers.

So to sum it all up, Clarkdale on paper is a very strange and intriguing project. It makes use some of the latest and greatest Intel technology in pair with some of the most criticized silicon they have (IGP). You can't do gaming with this processor alone, and if you're going for external graphic performance, wouldn't Core i5 750 be a far better choice? On the other hand, do you really need a $200 chip for a HTPC or office work? Well, only time and benchmarks will answer that question, and there's a whole lot of results on the next couple of pages.