Intel's Core i7 870 & i5 750, Lynnfield: Harder, Better, Faster Stronger
by Anand Lal Shimpi on September 8, 2009 12:00 AM EST- Posted in
- CPUs
Lynnfield's Un-Core: Faster Than Most Bloomfields
A few years ago I had a bet going with AMD's Ian McNaughton. We were at an AMD event where the Phenom architecture was first being introduced and he insisted that the L3 cache was part of the memory controller. This didn't make any sense to me so I disagreed. Minutes later a presentation slide went up on a projector talking about how the L3 cache and memory controller were on the same voltage plane; that's what he meant. Ian laughed a lot and to this day he holds it over my head.
The moral of the story is in Phenom and later in Nehalem, the processor is divided into two parts. Intel named them the core and the un-core. The "core" of these multi-core processors is made up of each individual processor core and its associated private caches (L1/L2). The "uncore" refers to everything else: PCIe controller, memory controller, DMI/QPI and the L3 cache.
The uncore isn't as critical for performance but is made up of a ton of transistors; roughly 400 million in the case of Lynnfield/Bloomfield (more if you count the PCIe controller). In order to save power, Intel uses slower transistors that have lower leakage for the un-core. As a result, the un-core can't clock up as high as the core and runs at a lower multiplier.
Take the Bloomfield Core i7 975 for example. The core runs at 25x BCLK (25 x 133MHz = 3.33GHz), but the un-core runs at 20x BCLK (20 x 133MHz = 2.66GHz). The rest of the chips, including Lynnfield, have slower un-cores:
| CPU | Socket | Core Clock | Un-Core Clock |
| Intel Core i7 975 Extreme | LGA-1366 | 3.33GHz | 2.66GHz |
| Intel Core i7 965 Extreme | LGA-1366 | 3.20GHz | 2.66GHz |
| Intel Core i7 950 | LGA-1366 | 3.06GHz | 2.13GHz |
| Intel Core i7 940 | LGA-1366 | 2.93GHz | 2.13GHz |
| Intel Core i7 920 | LGA-1366 | 2.66GHz | 2.13GHz |
| Intel Core i7 870 | LGA-1156 | 2.93GHz | 2.40GHz |
| Intel Core i7 860 | LGA-1156 | 2.80GHz | 2.40GHz |
| Intel Core i5 750 | LGA-1156 | 2.66GHz | 2.13GHz |
Here's another area where Lynnfield is better than the lower end Bloomfields: its uncore runs at 2.40GHz instead of 2.13GHz. The exception being the Core i5 750, its uncore is stuck at 2.13GHz as well. Once again, only the "Extreme" Bloomfields have a faster uncore.
Lynnfield's Memory Controller: Also Faster than Bloomfield
Intel only officially supports two memory speeds on Bloomfield: DDR3-800 and DDR3-1066. Obviously we're able to run it much faster than that, but this is what's officially validated and supported on the processors.
Lynnfield is a year newer and thus gets a tweaked memory controller. The result? Official DDR3-1333 support.
Three Lynnfield memory kits (left to right): OCZ, Patriot and Kingston
The same sort of rules apply to Lynnfield memory kits that we saw with Bloomfield. You don't want to go above 1.65V and thus all the kits we've seen run at 1.5V for the stock JEDEC speeds or 1.65V for the overclocked modules.
Like Bloomfield, 1.65V is the max we'll see on Lynnfield
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jonup - Tuesday, September 8, 2009 - link
Unfortunately people in corporate world do not make a difference between a HD4500 and a GX790. As lond as the Intel can display spreadsheets its good enough (or better) than a GTX295/HD4890X2, because it is Intel. You can change ignorance when it works.PassingBy - Tuesday, September 8, 2009 - link
My horizons are broad enough, thank you. The needs of many corporate desktops/laptops will be met by Clarkdale/Arrandale and no, nobody will go blind or suffer eyestrain (by virtue of the IGP anyway).PassingBy - Tuesday, September 8, 2009 - link
No edit function, so, as I point out later in the thread, people reading this review presumably won't be interested in IGPs anyway, given that these processors now have no IGP market. Wait for Clarkdale before trying to compare IGPs.dragunover - Tuesday, September 8, 2009 - link
Thanks for the review, if not as soon as I wanted it!Boobs McGee - Tuesday, September 8, 2009 - link
Do you guys have plans to do a motherboard review roundup for P55?If not, please do.
Gary Key - Tuesday, September 8, 2009 - link
I actually have three roundups planned, we have 15 boards here ranging from the $100 uATX items up to the $300 EVGA Classified series. We are only testing with retail products, released BIOS', and retail processors so the delivery of more than 70% of the boards late last week has created a small logjam. ;)The first article should be up on Thursday with a couple of my favorite boards and then a rather large one up on Monday and the last one a few days after that. Raja is working on a separate roundup of the top three boards targeted for the more extreme OC community. We will also have a P55 memory specific article shortly.
ClagMaster - Tuesday, September 8, 2009 - link
Looking forward to reading these P55 motherboard roundups.Anand Lal Shimpi - Tuesday, September 8, 2009 - link
Yes, Gary is nearly complete with his. Give him another day and it'll be up :)Take care,
Anand
Comdrpopnfresh - Tuesday, September 8, 2009 - link
By creating a new socket- they're providing a disincentive for early adopters of bloomfield. This chip is literally a humpty-dumpty that stands to benefit intel with everyone suffering a small loss of their own. The benefits of lynnfield vs bloomfield come from shuffling the architectural deck of nehalem. In reality, it only shows the possibilities of an inflexible architecture.The turbo mode isn't cutting it in day-to-day power consumption reduction. On the scale of a day, the average shmoe who is ass enough to leave a computer on for no reason gains no benefit. Lower the reach of a voltage plane, and reduce the number of components sucking juice, that only present benefits under certain situations (a third memory channel), and shmoe is happier.
If it was in the article, I apologize, but with the pci-e controller being on the un-core... what happens on a chipset with integrated graphics? Will the igp be linked to the processor now, rather than a bridge chip? If ati or nvidia made their own supporting chipsets with an igp- would the igp represent a chip onto itself, solely connected to the cpu, or would it have to work through dmi, and leave those on-die pci-e lanes for domestic usage?
It seems this is the warning rattle to nvidia that they chose their place with ion, and are stuck in it. When the change to 32nm comes, and the gpu is integrated into the cpu- what kind of robust 3rd party chipsets could exist in the budget end? Sure, you can always add a dedicated, off-die, gpu... but for budget boards used to eons of making room for a cpu and working a bridge chip around an igp- either horrible inefficiencies will creep up, or higher prices.
My money is on westmere having at least three power planes.
I'd like to know: with the pci-e controller on-die now... what impact this puts on graphics cards with higher on-card memory. Does it strengthen or minimalize it?
And, can the cpu now share the gpu's memory as a way to extend cache- after years of being forced to share the system pool. That 16gb/s link to gddr5 looks mouthwatering. I'd like to see performance tests run with the pci-e varient ssds floating around out there saddled to the on-die pci-e lanes, and a graphics card running off of chipset. Rather than elevating a horse-power driven graphics subsystem, I think the benefits of supplying more 'torque' by freeing mass storage ssds from the SATA interface would be far more substantial, and in all applications of the PC. You already have the means for nearly 2+2/3 times the theoretical bandwidth of SATA-6- which up til now seems rather bug-ridden and defunct.
Also interested in the outcomes of usb3 with this- as usb is built on the foundations of pci-e, is it not? If usb3 can allow for pci-e externally, and you remove the latency issue of usb signaling traveling from some peripheral bridge chip to the cpu, and just jack the usb3 communications into the cpu... could one use usb3 as a computer-to-computer psuedo qpi teaming/networking bridge for inter-desktop cpu communication. skip the entire bottleneck of client-level software implementation, and the subsystem communication buses for out-of-box signaling too...
plague911 - Tuesday, September 8, 2009 - link
The market just got a little more crowded so hopefully this will bring a reduction in prices of the 920. but..
“The Core i7 870 gets close enough to the Core i7 975 that I'm having a hard time justifying the LGA-1366 platform at all. As I see it, LGA-1366 has a few advantages:
1) High-end multi-GPU Performance
2) Stock Voltage Overclocking
3) Future support for 6-core Gulftown CPUs
“
Your exactly right 1366 I think is going to be be the best option to “future proof” my system however the new chips make the 920- seem a little low on features. With the goal of “performance on a budget” I feel like we are stuck either getting a board with a socket which wont compete in the future, or chip which is weaker than its lower class cousins. Unfortunately I dont see any of this being fixed in the next few cycles. Id like to see a low clocked gulftown (to save cost) feature rich with good OC potential thats on the lower end of the price scale. To me this would be a good follow up to 920 but but it dosent seem like that will be coming out for several cycles. Unless ofc i'm missing something which is probably the case.