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
JonnyDough - Thursday, September 10, 2009 - link
Were you purposely reiterating my point? :DI don't think AMD ever much cared about what Intel was doing. In business class I was taught to keep an eye on a competitor but to really focus on what you are doing. I think AMD was planning their next move, and it had little to do with what Intel was doing or planned on doing, but rather the reaction of what Intel would do when they created Athlon and the next step to being a successful innovative company. Going graphics was just a logical step, since NVidia had no real competition in this space. They saw a market that was ruled by two giants, and decided to combine technology. I'm not so sure that Intel had the idea first. Don't forget, there are leaks in this industry, and people are getting paid to snitch.
tajmahal - Tuesday, September 8, 2009 - link
This is the first time i've ever seen an article written using wholesale x 1,000 prices. Is there any reason you didn't take the trouble to post actual retail pricing?JonnyDough - Tuesday, September 8, 2009 - link
He probably wrote this article prior to today and based it off Intel's pricing scheme...I would think you'd probably gather that. NewEgg is also not the only E-tailer/Retailer out there...ViRGE - Tuesday, September 8, 2009 - link
The last time I checked, those are the only prices Intel gives out. The actual retail prices are a combination of what the retailer paid (buy more, spend less) and whatever markup they add. Intel doesn't have an MSRP.tajmahal - Tuesday, September 8, 2009 - link
i5 750 = $210i7 860 = $300
i7 870 = $580
Just in case someone wants to buy just 1 instead of 1,000. Newegg prices
Gary Key - Tuesday, September 8, 2009 - link
"i5 750 = $210i7 860 = $300
i7 870 = $580
Just in case someone wants to buy just 1 instead of 1,000. Newegg prices "
Retail prices fluctuate greatly at launch. This is what I paid for our retail processors with tax mind you. ;)
i5 750 = $205
i7 860 = $306
i7 870 = $564
cycleback - Tuesday, September 8, 2009 - link
Could you post some Linpack and finite element code benchmarks. This would approximate a larger number of HPC workloads. I would really appreciate this as it is difficult to find these sorts of benchmarks. It would also really test the difference in memory bandwidth between Bloomfield and Lynfield.tacoburrito - Tuesday, September 8, 2009 - link
From the benchmarks, the i7 920 and the i5 seems to be even; each winning about half the benchmarks. If costs for both are the same (proc and mobo), I think I'd still go with the 920. Of course I can stop being a cheap bastard and spring for the i7 860.tacoburrito - Tuesday, September 8, 2009 - link
I also meant to add that it should just be a matter of time before Intel cut the prices of the 920.TA152H - Tuesday, September 8, 2009 - link
One thing that's obvious is, after reading this, that the esteemed reviewer modified his review in order to fulfill his preconceived ideas of what he wanted to say. It's really a terrible review.Most people know this site isn't technical, but still, I always thought it was unbiased. It's biased, big time, just not for a company. It's about making a review say what they want.
For example, I doubt Anand is really as stupid as he sounds in this article. LGA1366 has so many advantages, certainly he knows this. But why the idiotic remarks about asking why it exists?
Why did this review ignore the fact that most people here overclock? Why did it ignore that most people reading these reviews won't use DDR3 1066 memory? Did this site just try to become PC Magazine without the writing talent, and go stock? I think not. It was because they only wanted to give information that was consistent with their preconceived idea.
But, let's look closer. The memory controller on the Bloomfield is actually faster than the Lynnfield when using the same memory, even when running in dual channel mode. Why wasn't it mentioned here?
Why wasn't a clock normalized comparison between the LGA1366 processors and LGA1156 processors made, or even attempted, to get an idea of what the architecture changes accounted for? Strange that this very important data is missing? I think so.
Why weren't overclock processors compared? I mean, will anyone here buy an i7 920 and not overclock it? Probably not many. Since the only real advantage is the more aggressive turbo mode, this was what the article was based on. But, in reality, for readers here, it's not important, since people are going to overclock, and the i7 920 would wipe the floor up with the Lynnfields in the configuration that would be used. Why no mention of this?
There are better sites that have answered these questions. I used to like this site, but this review is another disappointment.
Let's be real though, it looks like the processor's horrible performance in the pre-release configuration is just a bad memory. It's not a bad part by any stretch, but it's hardly made the LGA1366 useless, or even the i7 920. The technical savvy will still opt for it in a lot of instances, since they will overclock it. If you have to recommend something for a friend that won't, these things are fine.
Another really stupid remark was how AMD processors would only make sense if they drop the price. Have you forgotten AMD processors are coupled with excellent IGPs? That's been the big selling point for a while, and this hasn't really changed that, too much. IGP platforms are really big in sales too, so, I'd agree with the premise that AMD probably should lower their prices a little, but not that they don't have advantages even where they are. The processors don't, but you can't get an Intel motherboard with the 790GX either. And if they come out with something better, as rumored, it's just going to give their platform another advantage to help counteract their horrible processors (yes, I agree they suck).