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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snakeoil - Tuesday, September 8, 2009 - link
and the cherry on top of the piecore i5 750 and core i3 don't support virtualization.
http://www.virtualization.info/2009/07/intel-core-...">http://www.virtualization.info/2009/07/intel-core-......
that's fantastic, colossal intel.
what's wrong with intel
Anand Lal Shimpi - Tuesday, September 8, 2009 - link
Intel VT-x is supported by the Core i5 750:http://processorfinder.intel.com/details.aspx?sSpe...">http://processorfinder.intel.com/details.aspx?sSpe...
Take care,
Anand
snakeoil - Tuesday, September 8, 2009 - link
sorry incomplete linkhttp://www.virtualization.info/2009/07/intel-core-...">http://www.virtualization.info/2009/07/...core-i3-...
AssBall - Tuesday, September 8, 2009 - link
What are you talking about? These overclock FINE; read the article. 4 Ghz. Anyone that is gonna overclock bloomfield or lynnfield seriously is opting for an aftermarket HSF, so don't bother arguing that. Your comment doesn't make any sense.TA152H - Tuesday, September 8, 2009 - link
You missed the point.When you overclock the processors, you change the characteristics of turbo mode. Consequently, the big advantage of the Lynnfield disappears, and they run at the same clock speed, instead of the Lynnfield at a higher clock speed.
Do you understand now?
eternalfantasy - Tuesday, September 8, 2009 - link
lolemogoinginstyle - Tuesday, September 8, 2009 - link
"There are better sites that have answered these questions. I used to like this site, but this review is another disappointment. "Just how is that Tom's Hardware gig working out for you? I noticed your name was not on any of their launch reviews since you seem to be an expert on the subject. Why is that?
TA152H - Tuesday, September 8, 2009 - link
Thanks for asking.When I have time, I will be writing another article, which they hopefully will use, but to be honest, the time it takes to write an article, at least a well-written one, takes an enormous amount of time and effort.
Getting and verifying data is only part of it. Writing it in an artistic an interesting way is very time consuming, and, at least for me, requires many rewrites of the same pages. Each page took me at least five hours, some many more, plus the upfront time of deciding which pages to write, which probably took at least 30 hours of research.
The editor of Tom's wrote their articles, and it's clear to see the much more thorough review he did. Personally, I like him and occasionally do communicate with him, and I probably would like Anand too, since he seems like a good fellow, but I have no real affiliation with their site. If I write an article they like, they might publish it. That's it.
But, honestly, if you do it for money, you're a fool. It takes WAY too much time for that. You really have to want to do it, and the money is secondary.
goinginstyle - Tuesday, September 8, 2009 - link
So it took you five hours a page to do a copy and paste from Wikipedia on that so called article of yours? I read the Tom's P55 article, not seeing how it was any more thoughtful than the one here or at Tech Report. At least Anand did some searching and reported on items like PCIe clocking/voltage requirements that I noticed was not mentioned at Toms.Your only motive for these posts is to try and look impressive at Toms in hopes that they will publish another boring piece of dung from you. Otherwise, your complaints here are just as justified at Toms or TR, yet you are not posting at either site. That is why it is so obvious as to what you are up to with the flame bait comments.
TA152H - Tuesday, September 8, 2009 - link
I never even looked at Wikipedia, since I don't consider it a valid source of information.Why do you talk about things you don't know about. In fact, some people used Wikipedia to argue some points with me. I made a point never to look at those pages.
But again, what have you done with your, except produce carbon dioxide and speed up global warming? You seem pretty worthless to me.