Core i5 650 - 660 and 661 processor review

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Meet Clarkdale


Meet Mr. Clarkdale

Intel in the past few months began volume manufacturing its 32nm shrink of its Core microprocessor line, which the company refers to by the code name of 'Westmere'. Within the Westmere range you'll find the 'Dales' chips -- 'Clarkdale' for the desktop, and 'Arrandale' for the notebook. Our focus today is Clarkdale.

Clarkdale based processors will have two physical (execution) CPU cores each capable of two (hyper) threads (making 4 logical cores), and include integrated graphics and a memory controller. Like other Nehalem derivatives, Clarkdale will feature Intel Turbo Boost. The processors feature 4MB of Intel Smart Cache and an Integrated Memory Controller (IMC) that supports two-channels of DDR3 memory at officially supported speeds of up to 1333MHz. The cache memory consists of a 32KB L1 Data cache, 32KB Instruction cache and 256KB L2 cache per core. Then there's a nice L3 cache that is shared in-between the two CPU cores which is 4MB in total.

Today we thus see the light of the first Clarkdale CPUs - part of the Westmere family, or 32nm Nehalem family die shrink. We'll be focusing solely on the Core i5 range as Intel did not ship out Core i3 processors. Within the Core i5 600 range a total of four models are being released; Core i5 650, 660, 661 and 670, clocking in at 3.2, 3.33, 3.33 and 3.46GHz respectively. They will be priced at $176, $196, $196 and $284. Have a peek at the chart below.

Processor Base Clock Turbo
Core / Threads Cache Memory TDP Price
Core i5 670 3.46 GHz 3.73 GHz 2/4 4MB DDR3 1333 73W $284
Core i5 661 3.33 GHz 3.60 GHz 2/4 4MB DDR3 1333 87W $196
Core i5 660 3.33 GHz 3.60 GHz 2/4 4MB DDR3 1333 73W $196
Core i5 650 3.20 GHz 3.46 GHz 2/4 4MB DDR3 1333 73W $176
Core i3 540 3.06 GHz N/A 2/4 4MB DDR3 1333 73W $133
Core i3 530 2.93 GHz N/A 2/4 4MB DDR3 1333 73W $113

All Clarkdale CPUs come with an IGP on die which means it has a small embedded GPU inside the processor. Though the processors will be manufactured at 32nm the totally weird thing is that the graphics core is produced at 45nm. That can only mean one thing, the Clarkdale processors will feature a multi-chip package, the CPU and GPU won't be merged into a single die but will have two chips in one package. I obtained a beautiful photo showing this:


To the left you can see Core i5 600 (Clarkdale) with two separate chips on one package -- connected like Siamese twins. To the right the H55 PCH (motherboard chipset). From an architectural point of view this means that Clarkdale is a chip that's internally connected to a separate 45nm silicon that houses the GPU and dual-channel memory-controller - all in the same package.

An Embedded GPUThe IGP inside the processor is called the Intel Graphics Media Accelerator HD, and is derived from existing Intel graphics products. But with some nice new improvements. Thanks to the IGP connectivity this can be good, bringing native support for HDMI (v1.3), DVI and DisplayPort.

Category Features LGA 775 + Intel G45 Intel Series 5 IGP
Improvements Unified Shader architecture 2nd Generation 3rd generation
Execution Units (shader processors) 10 12
HW Vertex Processing Enhanced Enhanced cull/clip/setup
Hierarchical Z and Fast Z clear No Yes
Targeted OS optimizations Windows XP/Vista Windows XP/Vista/7
3D Performance Core Frequency Up to 800 MHz Up to 900 MHz
Max. Video Memory Up to 768 MB Up to 1.7 GB
DirectX DX 10 DX 10
Open GL 2.0 2.1
Shader Model SM 4.0 SM 4.0
Max Resolution 2560x1600 2560x1600
Dual Simultaneous HDMI No Yes

As you can observe from the specifications, don't expect heaps of gaming and fragging fun (though very simple games should be able to be played) but see this more as a desktop integration and implementation for very good Windows usage and importantly... high-definition 1080P decoding and acceleration.

Now back to the CPU part, you have probably already noticed that the Core i5 660 and 661 models seem to have the the same clock frequency. It is in fact the same processor with the same features, however on the 661 model the IGP will be clocked higher at 900 MHz and thus runs GPU accelerated applications slightly better. The IGP gets a perfect score in the HQV benchmark and Blu-ray, Dolby DTS, and other audio formats will be supported over the HDMI output making the Core i5 600 series a good HTPC alternative.

And then we land at the Core i3 530 and 540 covering the $123-$150 price range. The Core i3 processors will not feature Turbo mode, that will be the main difference. Other than that it's the same chip with the same features and TDP (73W).

One last thing I need to mention, Clarkdale (Core i5 dual core) processors are based on socket LGA1156 that currently powers Lynnfield CPUs (Core i5 750 / Core i7 860/870). We'll talk about this a little more in the chipset chapter.

Intel Core i5 661 (Clarkdale)

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