Intel Lynnfield Core i5-750 & Core i7-870 Processor Review

by MAC     |     September 6, 2009

Lynnfield - Core i5 & Core i7

Now that the media embargo has ended - and it was a particularly painful embargo for us since the retail processors and motherboards were being sold left, right, and center - we can finally reveal (or least confirm) everything you have wanted to know about the immediately available new Core i5-700 series and Core i7-800 series processors, codenamed Lynnfield.

First and foremost, let's talk about the naming scheme, arguably the most controversial aspect of this new processor family. Generally speaking, most people agree that the inclusion of Lynnfield models into the Core i7 series will confuse a great number of consumers, and it has...if our forums are anything to go by. However, it is what we're stuck with at the moment, so let's try to break down the product segmentation as best as we can. Intel have chosen this naming scheme to help highlight the specific technologies that each processors series supports. Simply put, Core i7 models are eight-thread processors which feature both Hyper-Threading and Turbo Boost technology. The Core i5 models are four-thread processors which support Turbo Boost, but not Hyper-Threading. Lastly, we eventually expect some additional Core i3 and/or i5 models with two-cores, Hyper-Threading, Turbo Boost, and even an IGP. One thing that all these chips share in common though is the socket: LGA1156. Even though the "i7" denominator may make them look compatible, none of these processors will fit into an LGA1366 X58 motherboard.

Clear enough? Good, let's take a closer look at what these new chips have to offer.


As you can see, the three initial launch models are somewhat similar, but there are notable differences based on the aforementioned i5/i7 segmentation. Fundamentally speaking, all three processors are based on the exact same core, but the i5-750 model has the Hyper-Threading (HT) feature disabled. The i5 model is further limited by the fact that it can only Turbo Boost up by four multipliers, while i7-860/870 have access to five additional multipliers, which equates to 666Mhz of core clock headroom. The i7-800 series models are not only HT-enabled, and have more aggressive Turbo Boost profiles, but they also benefit from a higher Uncore frequency, which means that their integrated memory controller (IMC) and L3 cache are operating faster than that of the i5-750 model. Having said that, while limited compared to its peers, the i5-750 does have a very attractive $199 price tag, especially compared to the ultra-pricey i7-870, which encroaches into i7-950 territory and defies its supposedly 'mainstream' roots. It is pretty clear to us that Intel is trying to channel consumers towards the i7-860 model, but we will have to see whether its performance warrants that 43% premium.

Packaging & Chips:

A new product launch requires a new packaging design, and both Core i5-700 series and Core i7-800 series processors will ship in this attractive new box (with appropriate i5/i7 designation, of course).

Bloomfield Cooler vs. Lynnfield Cooler - Click on image to enlarge

Intel has designed a new stock cooler for Lynnfield and it is tiny! It is a typical Intel design, featuring an aluminium body with an integrated copper core, and push-pins as the mounting system. Evidently, they are quite confident in their 95W TDP rating, since this cooler is significantly smaller than the one that ships with the 130W Bloomfield Core i7 chips. This potentially bodes well for overclockers though, since these must be really cool running chips, and we will definitely testing to see how well this cooler manages to cool Lynnfield at full load.

The Stars: i5-750 on the left, i7-870 on the right - Click on image to enlarge

To the untrained eye, Lynnfield processors look identical to Bloomfield chips, however the placement of the gold contact dots and the two 'wings' that protrude from the integrated heatspreader (IHS) are dead giveaways. Needless to say that these are both engineering samples, and thus the stepping is different from what you will find in the retail channel. However, the cores themselves are identical.

Click on image to enlarge

As per the LGA1156 socket name, those are 1156 contact points, a decrease from the LGA1366 Core i7 900 series, but still a huge increase from the 775 that are found on all Core 2 models. The layout of the micro SMD resistors is very interesting because it mimics the layout of the actual core, which you can see on the next page.

Bloomfield / Lynnfield / Core 2 Quad / Phenom II - Click on images to enlarge

When placed side-by-side, you can clearly see how much smaller the Lynnfield chip is compared to the Bloomfield, and this despite the fact that Lynnfield actually has a slightly bigger core. The reason? Well, the LGA1366 package was designed with future headroom in mind, specifically larger six-core and maybe even eight-core dies. It is also worth noting that the Lynnfield chip is actually exactly the same size as the venerable Core 2 Quad.

Don't expect to see these stock values often with Turbo Boost enabled - Click on image to enlarge

As usual, the CPU core speed is derived by a multiplier times bus speed formula. Since the FSB is no longer present, the bus speed in question is the base clock (BCLK), which has a stock frequency of 133MHz. As mentioned above, although our chips are engineering samples, they are manufactured with the final retail stepping, so they perform the same as the chips you will be able to buy in the retail channel.

i5-750 on the right, i7-870 on the left - Click on image to enlarge

The integrated memory controller and the L3 cache operate on a seperate frequency called the Uncore clock (NB frequency in CPU-Z), which is derived by the uncore multiplier time the base clock (BLCK). The i5-750 model has a 16X uncore multiplier and a 2133Mhz Uncore frequency. The i7-860 and i7-870 chips have an 18X uncore multiplier and a 2400Mhz Uncore frequency. One very exciting change with Lynnfield is that the Uncore has now been isolated from the DDR3 memory frequency, which means that Lynnfield can potentially achieve much higher memory speeds since it is no longer artifically limited by the Uncore ratio.

Now letís take an in-depth look at the Nehalem microarchitecture upon which these Lynnfield processors are based.

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