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 Turbo Mode: Up to 17% More Performance
Turbo on Bloomfield (the first Core i7) wasn't all that impressive. If you look back at our Core i7 article from last year you'll see that it's responsible for a 2 - 5% increase in performance depending on the application. All Bloomfield desktop CPUs had 130W TDPs, so each individual core had a bit more breathing room for how fast it could run. Lynnfield brings the TDP down around 27%, meaning each core gets less TDP to work with (the lower the TDP, the greater potential there is for turbo). That combined with almost a full year of improving yields on Nehalem means that Intel can be much more aggressive with Turbo on Lynnfield.
| SYSMark 2007: Overall | Dawn of War II | Sacred 2 | World of Warcraft | |
| Intel Core i7 870 Turbo Disabled | 206 | 74.3 fps | 84.8 fps | 60.6 fps |
| Intel Core i7 870 Turbo Enabled | 233 | 81.0 fps | 97.4 fps | 70.7 fps |
| % Increase from Turbo | 13.1% | 9.0% | 14.9% | 16.7% |
Turbo on Lynnfield can yield up to an extra 17% performance depending on the application. The biggest gains will be when running one or two threads as you can see from the table below:
| Max Speed | Stock | 4 Cores Active | 3 Cores Active | 2 Cores Active | 1 Core Active |
| Intel Core i7 870 | 2.93GHz | 3.20GHz | 3.20GHz | 3.46GHz | 3.60GHz |
| Intel Core i7 860 | 2.80GHz | 2.93GHz | 2.93GHz | 3.33GHz | 3.46GHz |
| Intel Core i5 750 | 2.66GHz | 2.80GHz | 2.80GHz | 3.20GHz | 3.20GHz |
If Intel had Turbo mode back when dual-cores first started shipping we would've never had the whole single vs. dual core debate. If you're running a single thread, this 774M transistor beast will turn off three of its cores and run its single active core at up to 3.6GHz. That's faster than the fastest Core 2 Duo on the market today.
WoW doesn't stress more than 2 cores, Turbo mode helps ensure the i7 870 is faster than Intel's fastest dual-core CPU
It's more than just individual application performance however, Lynnfield's turbo modes can kick in when just interacting with the OS or an application. Single threads, regardless of nature, can now execute at 3.6GHz instead of 2.93GHz. It's the epitomy of Intel's hurry up and get idle philosophy.
The ultimate goal is to always deliver the best performance regardless of how threaded (or not) the workload is. Buying more cores shouldn't get you lower clock speeds, just more flexibility. The top end Lynnfield is like buying a 3.46GHz dual-core processor that can also run well threaded code at 2.93GHz.
Take this one step further and imagine what happens when you have a CPU/GPU on the same package or better yet, on the same die. Need more GPU power? Underclock the CPU cores, need more CPU power? Turn off half the GPU cores. It's always availble, real-time-configurable processing power. That's the goal and Lynnfield is the first real step in that direction.
Speed Limits: Things That Will Keep Turbo Mode from Working
As awesome as it is, Turbo doesn't work 100% of the time, its usefulness varies on a number of factors including the instruction mix of active threads and processor cooling.
The actual instructions being executed by each core will determine the amount of current drawn and total TDP of the processor. For example, video encoding uses a lot of SSE instructions which in turn keep the SSE units busy on the chip; the front end remains idle and is clock gated, so power is saved there. The resulting power savings are translated into higher clock frequency. Intel tells us that video encoding should see the maximum improvement of two bins with all four cores active.
Floating point code stresses both the front end and back end of the pipe, here we should expect to see only a 133MHz increase from turbo mode if any at all. In short, you can't simply look at whether an app uses one, two or more threads. It's what the app does that matters.
There's also the issue of background threads running in the OS. Although your foreground app may only use a single thread, there are usually dozens (if not hundreds) of active threads on your system at any time. Just a few of those being scheduled on sleeping cores will wake them up and limit your max turbo frequency (Windows 7 is allegedly better at not doing this).
You can't really control the instruction mix of the apps you run or how well they're threaded, but this last point you can control: cooling. The sort-of trump all feature that you have to respect is Intel's thermal throttling. If the CPU ever gets too hot, it will automatically reduce its clock speed in order to avoid damaging the processor; this includes a clock speed increase due to turbo mode.
Lynnfield and its retail cooler
The retail cooler that ships with the Core i7 is tiny and while it's able to remove heat well enough to allow the chip to turbo up, we've seen instances where it doesn't turbo as well due to cooling issues. Just like we recommended in the Bloomfield days, an aftermarket cooler may suit you well.
Lynnfield: Made for Windows 7 (or vice versa)
Core Parking is a feature included in Windows 7 and enabled on any multi-socket machine or any system with Hyper Threading enabled (e.g. Pentium 4, Atom, Core i7). The feature looks at the performance penalty from migrating a thread from one core to another; if the fall looks too dangerous, Windows 7 won't jump - the thread will stay parked on that core.
What this fixes are a number of the situations where enabling Hyper Threading will reduce performance thanks to Windows moving a thread from a physical core to a logical core. This also helps multi-socket systems where moving a thread from one core to the next might mean moving it (and all of its data) from one memory controller to another one on an adjacent socket.
Core Parking can't help an application that manually assigns affinity to a core. We've still seen situations where HT reduces performance under Windows 7 for example with AutoCAD 2010 and World of Warcraft.
With support in the OS however, developers should have no reason to assign affinity in software - the OS is now smart enough to properly handle multi-socket and HT enabled machines.
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goinginstyle - Thursday, September 10, 2009 - link
What is worthless here is your continued ramblings about subjects you have no actual knowledge of right now. Do you own a P55 system? If so, let's see an article from you. Really, you come over spouting off and calling everyone idiots, yet, you we do not see any articles from you at Toms about the subject matter. In fact, we do not see any comments from you anywhere else about P55. Toms, Tech Report, and AT all came to the same conclusion, presented the same type of information (although AT discussed subjects like PCIE), and yet you do not comment on those other websites.Either you are posting here because you think your negative posts will somehow get you attention that your mother never gave you or you are doing to try and look important to the people in charge at Toms. I hope to God that they never allow you to post another piece of garbage on their site. Really, that article was a straight copy and paste from several other articles on the subject along with Wikipedia information. I am surprised you were not sued for plagiarism, maybe you were and that is why you are over here.
So far, all of your ramblings have only proved your total lack of intelligence when it comes to computer components. Once again, when will we see you making comments on Toms about their similar coverage or when can you expect to see your expert PP article on the site?
eternalfantasy - Tuesday, September 8, 2009 - link
Fully agree up to the AMD part. This is the most biased review I've seen published by Anandtech to date. I think a "Buy me now!" link at the end of the article with an Intel sponsored Ad will complete the article perfectly.Stock clock speed CPU review is what highstreet mags for average Joes write about. Excluding what's importent for readers of tech sites, such as:
Clock for clock comparison
Maximum overclock with similer priced CPU/platform
is just blatent attempt at glorifying Intel's mainstream platform to look like more then what it really is. A cheaper mainstream alternative to the X58 that has been avaliable over a year ago.
PassingBy - Tuesday, September 8, 2009 - link
As released, Core i5 and 1156 Core i7 have no IGP market, so presumably people reading this review will have no interest in using an IGP.In any case, we can safely say that your prognostications like 'a brain dead platform for brain dead people' were total bullshit, as many people tried to tell you. Now, many more people can place a Nehalem-based system on their list of possible purchases. Clarkdale will extend Nehalem/Westmere to even lower price points (and yes, then you can start comparing IGPs, if you like).
TA152H - Tuesday, September 8, 2009 - link
You're really confused.Honestly, anyone who knows anything about computers would be pretty stupid to get this platform. It's fine stock, but when you throw in overclock, the i7 920 is the better choice.
But, here's your hypocrisy. This article was main for mainstream people, since there's no overclocking comparisons, really. The IGP is what makes AMD work, and they do sell their processors into this market. Anand was commenting on how AMD had to lower their prices, so within this context the entire market is applicable. You didn't understand the context, did you?
I didn't say the platform was brain-dead, although you seem to be. I said it was brain-damaged. It's a Celeron. If you look at the reviews from better sites, you can see the Bloomfield running at the same speed is faster than the brain-damaged Lynnfield. Anand really tried to obfuscate this, by using bad comparisons or those meant to show the Lynnfield in the best light, instead of just presenting the most useful information. He fooled you, because you're a moron, but not everyone.
I do like this site, or I did, but I'm really getting unnerved by the way they test to show what they want to show, instead of test and then make up their minds. It's really problematic, and it's going to bite them when more people figure this out.
imperialsoren - Tuesday, September 8, 2009 - link
You have a nasty way of conversing.IdolObserver - Wednesday, September 9, 2009 - link
It's not only his nasty way of conversing. He also doesn't have a clue what he is talking about.Zymon - Tuesday, September 8, 2009 - link
I agree in the main part - there are many aspects which seem to have been completely ignored in this, and many other reviews of Lynnfield.It seems strange that you haven't used a level playing field between compared systems: ALL 3 platforms can use DDR3 - you've used X48 for Core 2 chips, but apparently used different RAM than i5. Why on earth have you used an AM2+ board and DDR2 ram for AMD? I guess it's *only* been 9 months since AM3 became available?
As mentioned, a true clock-for-clock comparison would be VERY interesting, using the same RAM, at the same speeds and timings between platforms.
Anand Lal Shimpi - Tuesday, September 8, 2009 - link
Sorry if this wasn't made clear in the review but the Phenom II X4 965 BE used the same test platform as our review of that CPU: an AM3 motherboard with DDR3 memory.I'm out of the office now but I'll update the test tables later this evening to reflect this.
Take care,
Anand
Zymon - Tuesday, September 8, 2009 - link
Cheers for the clarification Anand!- It seemed unusual for one of your articles, hence the comment!
Laters..
snakeoil - Tuesday, September 8, 2009 - link
i want to know if those benchmarks were with the turbo enabled, which would be cheating, because that's overclocking.for every benchmark turbo must be disabled to be fair.
readers are not stupid.