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
Facebook
Twitter
RSS
343 Comments
View All Comments
snakeoil - Tuesday, September 8, 2009 - link
what part of stock speed you don't understand?if you are going to compare 2 processors both must have a fixed stock speed, if you increase the frequency of one of them by 1Ghz over the stock speed that is illegal.
or either both have a stock fixed speed to benchmark or both are overclocked.
overclocking is the same it doesn't matter if it's auto overclocking or manual overclocking.
we the people demand justice.
we the people are not stupid.
Anand Lal Shimpi - Wednesday, September 9, 2009 - link
You may find that your desire for fixed speed comparisons will become difficult in the future. Both AMD and Intel are going to be embracing this sort of an approach to clock speeds.Overclocking is not the same as what is happening with turbo mode. Overclocking is not officially supported by the manufacturer, it is running a part faster than it was sold at in order to improve performance. If an application crashes because you've overclocked your chip too far that's no fault of the manufacturer.
Turbo mode runs the chip at a frequency it's guaranteed to work at, it's operating within spec. It simply re-allocates thermal resources; Intel could disable 3 of the cores and sell a Core i7 870 as a 3.6GHz single-core processor, or disable 2 of the cores and sell it as a 3.47GHz processor, or only disable one core and sell it as a 3.2GHz processor. Instead of making the end user choose, instead you get a dynamic processor that can configure itself in real time depending on the workload.
This is in stark contrast to AMD's Overdrive utility which is actually overclocking. The chips aren't validated at the overdrive speeds and you're thus overclocking. Lynnfield is validated at both its standard clock speed and its turbo speeds, just like Bloomfield. So long as you don't exceed the TDP of the chip, it will work at those turbo frequencies. The things that will prevent it from turboing were outlined in the article.
Once again, I am not increasing the speed of anything - Lynnfield is simply working as designed. Whether it's in a Dell machine or in a custom build, it will always work this way. It's what the end user will see the moment they turn on a Lynnfield machine. The end user would not see the same from a Core 2 or a Phenom II based machine.
Take care,
Anand
Jamahl - Wednesday, September 9, 2009 - link
The problem with this review is it has a bunch of graphs with intel cpus with speeds rated at a lot lower than what they actually are.When you show a graph of an i5 @ 2.66 gigahertz beating a 3.4 gigahertz phenom II, that is false and that is a problem. This cpu was not ever at 2.66 gigahertz for any of these tests was it?
I suggest there is a problem with your reviewer also, not to mention his attitude about 'having a laugh' because i brought up this point?
Anand Lal Shimpi - Wednesday, September 9, 2009 - link
Again, that is the default clock of the processor - in many cases (especially the heavily threaded tests) it will be running at that speed. Turbo mode is dynamic, it's impossible to put down exactly what speed the chip was running at as it'll change throughout each test.You might see the chip run at 2.66GHz for several seconds, jump up to 3.46GHz then down to 3.2GHz, up to 3.6GHz and then back down to 2.66GHz all in the course of a single benchmark. It's repeatable, but there's no way to display all of that in a bar chart.
Take care,
Anand
snakeoil - Wednesday, September 9, 2009 - link
What you are doing is cheating, and people is not stupid.you are saying that lynnfield is faster than phenom 2 because lynnfield is overclocked at least 600 mhz.
people is not stupid as you think, and what you are doing is outrageous.
if you are going to benchamark with turbo enabled then you have to overclock phenom 2 at least the same 600 mhz.
show some respect for your readers. or are you really on intel's payroll?
Klober - Wednesday, September 9, 2009 - link
I am usually very respectful on the AnandTech and DailyTech forums and comments areas, but you sir are exactly as stupid as you are claiming people "is" not. Please read the article from beginning to end before continuing on your unjustified tirade. The processor is being used as intended by the manufacturer - to not test it in this way would be a disservice to the engineers who designed it and the company that produces it.snakeoil - Wednesday, September 9, 2009 - link
if you dont want to disable turbo the overclock phenom 2 at least 600 mhz.just to be fair.
Gary Key - Wednesday, September 9, 2009 - link
"if you dont want to disable turbo the overclock phenom 2 at least 600 mhz.just to be fair. "
You do realize that it takes near zero or sub-zero cooling to run the 965BE in stable manner at 4GHz with a 64-bit OS. When I say stable, I mean 24/7 multi-tasking, not a CPUZ screenshot or a SuperPi 1M bench. AMD has not solved this problem with the current stepping.
Once again, and for the last time, Intel's turbo function is a standard feature of the processor. AMD will be offering the exact same technology in their next processor family.
snakeoil - Wednesday, September 9, 2009 - link
that's not true.we demand justice and fair benchmarks.
you are losing all credibility and these benchmarks are worthless and unreal.
goinginstyle - Wednesday, September 9, 2009 - link
How many times do they have to respond to you in a logical manner. You should be banned and in some countries that would mean a beheading for being so damn stupid.