Intel Core i5 750 & Core i7 860/870 Review --- TheThirdMedia Hardware

Lynnfield Makes its Long Awaited Debut

Meet Lynnfield, Intel's latest processors that have been on the upcoming horizon for the longest time. The mainstream successor to Intel's Core 2 platform is based on the same 45nm Nehalem CPU microarchitecture as the Core i7 and it has finally arrived after being pushed back from its original July launch date. Much has been speculated about reasons for the delay of Lynnfield to the last quarter of 2009, though the general economic malaise certainly hasn't helped Intel's cause. In any case, we fancy that there should significant pent-up demand for new mainstream processors, what with Windows 7 launching next month.

The Lynnfield processor here is smaller due to the packaging as the die size is the same as Bloomfield. Here you can see the Core i7-870 on the left, compared to a Bloomfield Core i7.

Flipping them over, the pin count for the Lynnfield is obviously lower.

Physically, these mainstream Lynnfield chips are smaller overall than the current Bloomfield Core i7 models in the market despite having slightly more transistors. The packaging is the reason for the size shrink. With the processor's much lower pin, it doesn't make economical sense to continue using the more expensive LGA1366 socket and its platform. As such the Lynnfield processors use a new socket, LGA1156 coupled with a new platform (which we'll touch upon quite shortly). While they are Nehalem architecture based and have common characteristics like a similar amount of L2 and L3 cache, there have been some significant changes under the hood. Firstly, the integrated tri-channel memory controller has been reduced to a more conventional dual-channel controller that should be adequate for most mainstream users.

The die layout of a Lynnfield CPU is mostly similarl to the Bloomfield (Core i7) but the two QPI links are gone, with the new PCIe controller taking up a substantial chunk of the die instead.

Then there's the addition of an integrated PCIe graphics controller with 16 lanes of PCIe 2.0, removing another functionality from the motherboard chipset and bringing it into the processor. Of course, with its mainstream emphasis, some things had to go and the QuickPath Interconnect (QPI) links on the Bloomfield has been removed. One of Intel's older technologies, Direct Media Interface (DMI) is used instead to communicate with the chipset. Along with these changes, the cost of manufacturing has been lowered sufficiently for Intel to price them in the US$200 to US$600 range.

And it will be a new chipset that's doing the talking. Intel's P55 Express chipset, a new single chip design that does away with the North/Southbridge divide is currently the only one supporting the LGA1156 socket. We have previewed some of these P55 motherboards, like the ASUS P7P55 EVO,, the Gigabyte P55-UD6 and the MSI P55-GD80 and we'll be talking more about the Intel DP55KG reference board in a while.

Back to Lynnfield, Intel will be introducing three models this year, with more to follow in 2010. These processors are divided into two series, which is where the branding jargon gets confusing. First, there's the Core i5-750, with a nominal clock speed of 2.67GHz. The other Lynnfield processors however use the Core i7 moniker, the Core i7-870 and i7-860, clocked at 2.93GHz and 2.80GHz respectively.

In case you're wondering, there's a very important reason for this. The lower 700 series will not have HyperThreading as a feature, hence you can expect a maximum of four logical cores. The Core i7 800 series meanwhile will have HyperThreading onboard, though you can choose to disable it in the BIOS. The table below lists some of the important details about these available models:

The New Lynnfield Processors

Processor Model	Clock Speed	Max Turbo Frequency	L3 Cache	Cores/Threads	Direct Media Interface	Max TDP (W)	Retail Price (1K units)	Availability
Core i7-870	2.93GHz	3.60GHz	8MB	4/8	4.8GT/s	95W	~US$555	Now
Core i7-860	2.80GHz	3.46GHz		4/8			~US$285
Core i5-750	2.66GHz	3.20GHz		4/4			~US$199

Idling at the desktop, the Core i7-870 fluctuated within a range of multipliers (13x to 15x being the most common, but it can go down to 10x depending on the BIOS options you've used).

The most obvious difference between the 700 and 800 series Lynnfield processors is the lack of HyperThreading on the Core i5-750.

As you may have noticed from the table, these Lynnfield processors have a Max Turbo Frequency column, which is probably the most significant change from Bloomfield. If you can remember, the Core i7 introduced this feature with the Bloomfield Core i7, where the processor will automatically ramp up the clock speed (increase in the multiplier) when fewer cores are being taxed. Lynnfield brings an enhanced version of this, which we shall elaborate next.



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