I swear this is the longest it’s taken for an Intel architecture to penetrate the market. We first met Nehalem on November 3rd, 2008. It came to us as a high end quad-core processor and took a full year to make it to more affordable motherboards in the form of Lynnfield. Even with P55 motherboard prices down at the magical $99 marker, Intel relinquished control of the $100 - $200 CPU market without a Nehalem to compete down there. Instead we were left with a choice between Penryn, the update to Intel’s 2006 Conroe architecture, or Phenom II, AMD’s low-cost Nehalem competitor. The choice was simple.

From $100 to $200, your best bet has been AMD. Either through aggressive pricing on quad-core CPUs or the L3-cache-less Athlon II line, AMD controls the $100 - $200 market. Today we meet Intel's first 32nm CPUs, codename Clarkdale, designed to specifically target that $100 - $200 market.


Two cores, Nehale..err Westmere-style

Technically Clarkdale isn’t Nehalem, it’s Westmere. Take Nehalem, use 32nm transistors, add in some new instructions for accelerating encryption/decryption, and you’ve got the makings of Westmere.

Clarkdale uses a dual-core Westmere and sticks it next to a 45nm Intel GMA die. That’s right, meet the first (er, second) Intel CPU with on-chip graphics. Next year we’ll see Sandy Bridge bring the graphics on-die, but until then we have Intel’s tried and true multi-chip-package to tide us over.

We don’t get on-die graphics yet because Intel still hasn’t switched over to its make-everything-at-the-best-process-ever strategy. The 32nm fabs are ramping up with CPU production and the 45nm fabs need something to do. Nearly every desktop and laptop sold in 2010 will need one of these 45nm GMA die, so the fabs indeed have something to do.

It’s not all rosy with Clarkdale unfortunately. Remember the memory controller that Nehalem so graciously integrated? Clarkdale kicks it off die again. The IMC is housed in the 45nm GMA die. It’s still on-package, but not on-die. The benefit is super fast memory access for the graphics core, but slower memory access for the CPU core. In fact, this is a derivative of the memory controller used in older Intel chipsets (e.g. P45/X48).

The CPU connects to the GMA die using QPI, so bandwidth shouldn’t be as big of a problem. Latency is unfortunately hurt as a result. Access times can be longer than older LGA-775 processors thanks to this memory controller design being optimized for FSB architectures. Again, the problem goes away with Sandy Bridge, but today we’re faced with it.

Like Lynnfield, Clarkdale uses Intel’s LGA-1156 socket. Clarkdale should work in all P55 motherboards, but you’ll need a BIOS update. No existing P55 motherboards route video from the socket to a VGA/DVI/HDMI connector, so you’ll need a new motherboard if you want to take advantage of the on-package graphics. Enter the H55, H57 and Q57 chipsets.


A typical H57 I/O layout

The H and Q-series of chipsets feature what Intel calls its Flexible Display Interface (FDI). This is basically a link between the CPU and the chipset that passes along video output. H5x/Q57 motherboards will have a video out on board so you can use Clarkdale’s integrated graphics.

The chipsets differ in price and features. The table below sums it up:


Click to Enlarge

Support for Intel’s Rapid Storage Technology is probably the main reason you’ll want H57 over H55. The difference between H57 and Q57 boils down to security and management features. The H-series is for consumers, the Q-series is for corporate customers. Make sense?

The chips themselves are pretty straightforward. Intel is launching seven desktop Clarkdale processors (and a whole lot more notebook Arrandale chips):

Processor Core Clock Cores / Threads L3 Cache Max Turbo TDP Price
Intel Core i5-670 3.46GHz 2 / 4 4MB 3.76GHz 73W $284
Intel Core i5-661 3.33GHz 2 / 4 4MB 3.60GHz 87W $196
Intel Core i5-660 3.33GHz 2 / 4 4MB 3.60GHz 73W $196
Intel Core i5-650 3.20GHz 2 / 4 4MB 3.46GHz 73W $176
Intel Core i3-540 3.06GHz 2 / 4 4MB N/A 73W $133
Intel Core i3-530 2.93GHz 2 / 4 4MB N/A 73W $113
Intel Pentium G9650 2.80GHz 2 / 2 3MB N/A 73W $87

 

The six processors labeled Core i5s and Core i3s all have the same basic architecture. You get per-core 256KB private L2s and you get a 4MB L3 cache shared among both cores (down from 8MB from the quad-core Lynnfield/Bloomfield chips). The i5s get turbo mode while the i3s do not. The i5-661 uses a higher graphics clock and has a higher TDP than the 660. Remember that these are CPU+GPU combos on a single package, so GPU clocks do vary based on model.

The Clarkdale lineup is honestly made up of CPUs that are too expensive. The Core i5 670, 661/660 and 650 are all priced above $170 and aren’t worth the money. The problem is Lynnfield’s turbo mode gives you high enough clock speeds with two threads that there’s no need to consider a dual-core processor. You can buy a Core i5 750, have more cores than any of these Clarkdales and run at close enough to the same frequencies for $196. Or you can buy a Phenom II X4 965 for about the same price and have much better multi-threaded performance. The chips that are most interesting are the Core i3s.

Processor Clock Speed Max Turbo
2 Cores Active 1 Core Active
Intel Core i5-670 3.46GHz 3.60GHz +3.9% 3.73GHz +7.7%
Intel Core i5-661 3.33GHz 3.46GHz +4.0% 3.60GHz +8.0%
Intel Core i5-660 3.33GHz 3.46GHz +4.0% 3.60GHz +8.0%
Intel Core i5-650 3.20GHz 3.33GHz +4.2% 3.46GHz +8.3%
Intel Core i3-540 3.06GHz N/A
Intel Core i3-530 2.93GHz N/A

 

Turbo just isn't as interesting with only two cores. With four cores you used to have to make a tradeoff between good 4 and 2 threaded performance, but Lynnfield fixed that. No one really debates single vs. dual core anymore. The single core turbo modes are great, but aren't worth the money. Pay attention to the i3s.

Memory Performance - Not Very Nehalem
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  • yuhong - Monday, January 04, 2010 - link

    "The Clarkdale lineup is honestly made up of CPUs that are too expensive. The Core i5 670, 661/660 and 650 are all priced above $170 and aren’t worth the money. The problem is Lynnfield’s turbo mode gives you high enough clock speeds with two threads that there’s no need to consider a dual-core processor. You can buy a Core i5 750, have more cores than any of these Clarkdales and run at close enough to the same frequencies for $196."
    But then you have to pay extra for a discrete graphic card and not every application need the extra graphic power!
    Reply
  • Paulman - Monday, January 04, 2010 - link

    Wow, I was going to write about how you wouldn't have to buy a discrete graphics card if you went with a Core i5 750 because you could just choose a motherboard with an integrated graphics chip. But then I checked online and it seems that there aren't any P55-based boards with integrated graphics - wow! Wouldn't have believed it myself.

    However, Anand's point still stands when comparing the Clarkdale i5's to the Phenom II X4, for which you can get many boards with integrated graphics.
    Reply
  • Inkie - Sunday, January 10, 2010 - link

    "when comparing the Clarkdale i5's to the Phenom II X4, for which you can get many boards with integrated graphics"

    ...but Clarkdale already has integrated graphics.
    Reply
  • ssj4Gogeta - Friday, January 08, 2010 - link

    It's because P55 is a southbridge, not a northbridge. Reply
  • Taft12 - Monday, January 04, 2010 - link

    But then you have to pay extra for a discrete graphic card and not every application need the extra graphic power!

    Only if you don't already have any PCI-E x16 card. Is that true for a single reader of this site? And truly ANY PCI-E card will perform better than Intel's on-chip solution, even one 3 generations old.
    Reply
  • ereavis - Monday, January 04, 2010 - link

    so the price goes up another $30-$40. As to your question of truth, yes I spend 40 hours a week on an intel IGP dual core as it is, so do the other 1000 people in this building doing engineering work that's processor demanding but graphics independent. Reply
  • nubie - Monday, January 04, 2010 - link

    There are rafts of HP 8400 OEM pci-e cards on ebay right now for $15 (total, no shipping or tax), that should even accelerate your Flash 10.1 and video just fine.

    If you even need it that is, and it is clear that for many there is absolutely no use for more than the integrated graphics.
    Reply
  • oc3an - Monday, January 04, 2010 - link

    Hi Anand. Looks to me like something weird is up with your Everest benchmarks. Shouldn't the 24X multiplier have the faster scores?

    -Patrick
    Reply
  • Rajinder Gill - Monday, January 04, 2010 - link

    Hi Patrick,

    Fixed it, the images were reversed.

    Thanks!
    Raja

    Reply
  • maxfisher05 - Monday, January 04, 2010 - link

    Good Article Anand. I'm going to be building my first HTPC soon, but I want to be able to do some light gaming on it, and it doesn't look like the integrated graphics have come far enough yet. If the 661 was priced lower I would consider it, but for nearly the price of a 750 you are right in saying it makes no sense. 750 + 5750 discrete graphics for me please :)

    Will someone be posting an updated system buyers' guide soon?
    Reply

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