Intel Core i7

Intel Core i7-860 Lynnfield Processor Review - Best value in processors?

Date: Sep 15, 2009
Subject: Processor
Manufacturer: Intel
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Lynnfield Reaches Retail

Last week Intel's latest addition to its arsenal of desktop processors was released in the form of the Core i7 and Core i5 series' for the LGA1156 socket. These new cores, previously known as Lynnfield (and we will still call it as much throughout our reviews), differ from the previously available Bloomfield processors (only available as Core i7 CPUs for the LGA1366 socket) in a few ways:

* Dual-channel memory controller- Lynnfield does indeed still have an integrated DDR3 memory controller but here Intel has removed one of the channels from Nehalem to make the new core dual-channel. While this is theoretically a performance drawback, in real-world testing (as you will soon see) the third channel made very little performance difference in most consumer applications. By removing one channel Intel was able to make the CPU package smaller (less pins required), lower the cost of ownership (only two DIMMs needed now) while keeping performance very high.

* No QPI interface- While Nehalem used the QPI interface to communication with the north bridge of the motherboard, Lynnfield uses a connection called DMI. DMI is much slower than QPI (2 GB/s versus 26 GB/s or so) but in nearly all cases that bandwidth will be more than adequate for the amount of data moving between the processor and chipset even in a worst case scenario. Again, with this change, Intel was able to lower the pin count for Lynnfield in relation to Nehalem.

* Integrated PCI Express 2.0- A first for a consumer processor, Lynnfield actually takes 16 lanes of PCIe 2.0 and moves them onto the die of the processor itself. That means that the graphics cards (or any other PCIe devices) now communicate directly with the processor itself rather than through a north bridge or chipset controller. The advantage here is for a lower cost chipset though I am betting that performance advantages from this are going to be minimal to non-existent. This is basically another move towards a more highly integrated platform on the Intel CPU.

* Split HyperThreading integration- HyperThreading is still around on the Lynnfield processors, but it will only be enabled on SOME of the product offerings. While the die size and transistor counts will be exactly the same, Intel will basically just flip off the HyperThreading capability in order to create a market differentiation and pricing segmentation. More details on what CPUs have what on the next page.

* Larger Turbo Mode differentiations- While Lynnfield was being prepared Intel's engineers found out how to get a little more frequency out of the Nehalem architecture and you'll notice that when you see the larger Turbo Mode improvements on Lynnfield. Essentially, the cores have been fine tuned in a way that will allow them to auto-overclock higher than even the most expensive Core i7 processors available today.
I won't get into all of the architectural or product differences here, but if you are still a bit behind the curve in that regard you should definitely be checking out the previous Lynnfield launch review in which I go into great detail about all things new and old in the processor, motherboard chipset options, pricing and more.



Some of the most immediate feedback from my first article was the question "what about the Core i7-860 processor?" The first answer was that Intel just didn't sample those to us - but no worries, we took care of it. I ordered a retail version of the Core i7-860 online just a few hours after my review was published and following a short trip out to visit AMD to talk GPUs, I proceeded to run the CPU through the benchmarking gauntlet.



The retail packaging for the Core i7/i5 Lynnfield processors is basically the same as previous CPUs from Intel in recent memory and in the box you'll get the stock heatsink, the processor and some basic warranty information with a sticker on the back so you declare your fan-ship to the Intel brand.



As we discussed last week, the Core i7/i5/Lynnfield CPUs are based on the LGA1156 socket and will require you to have a motherboard based on the new P55 chipset to run.



As with all Lynnfield CPUs, the Core i7-860 runs at just 1.2 GHz when at idle with the EIST features enabled.


This is the maximum speed of the Core i7-860 with Turbo Mode enabled.

While we already tested the Core i7-870 and Core i5-750 processors, the Core i7-860 finds itself resting directly in the middle of those two parts in terms of clock speeds and Turbo Mode overclocking.



This table, taken from our initial Lynnfield review, shows us that while the base clock of the Core i7-860 runs at 2.80 GHz it can reach as high as 3.46 GHz depending on CPU utilization and thermals. In my testing, just as with the other Lynnfield parts, there was a very easy formula you could follow. The CPU would hit the 3.46 GHz mark whenever one to four threads were at work and would always run at least at 3.06 GHz and would step up to 3.33 GHz when fewer than 6 threads were at work in some cases. In general, we assumed a 3.06 GHz clock speed on a fully loaded system and a 3.46 GHz speed when otherwise crunching on single and lightly-threaded applications.

These results are basically one stepping (133 MHz) below those of the Core i7-870 processor - a difference made more manageable when you consider the nearly 2x price gap between the two CPUs. In fact, that price point of $285 or so is exactly why our readers demanded we test it in comparison to the Core i7-870 and i5-750...