Does Turbo Boost Help Or Hurt Core i5/i7's Power Efficiency?
Table of contents
- 1. LGA 1156 Core i5/i7 Efficiency Explored
- 2. Power Play On TDP
- 3. Test Setup
Intel’s new LGA 1156-based processors, namely the Core i5-700- and Core i7-800-series, arrived with a bang. Our launch article by Chris Angelini provides all the key information. But, in short, the new processor delivers increased performance compared to Core 2 Quad. No surprise there. But Intel also claims that power consumption went down significantly, so we decided to tackle this prospect with a closer look.
The Core i5 Innovation
The new P55 platform and Intel’s Lynnfield processors make a are impressive enough from a performance angle, but I’d like to look at the facts from a different perspective. The platform’s foundation still centers on the Nehalem architecture first seen as Core i7 for LGA 1366 late last year, hence the level of innovation in Lynnfield is less revolutionary and more of an evolution.
Intel is great at tweaking, though. From a technology standpoint, Core i5 incorporates a lot more integration, stepping closer to the inevitable SoC (system-on-chip) future by adding PCI Express onto the die. A more aggressive implementation of Turbo Boost adds extra performance for non-threaded applications. Considering that Intel plans to integrate graphics with Clarkdale in coming months, this step could also be looked at as a necessity. Improved Turbo Boost is another building block for turning dynamic overclocking into a real feature. In reality, though, the large motherboard makers have been offering similar features for a few years already.
I see two main benefits of the new LGA 1156 processors for buyers. First, you have decreased power consumption thanks to the integrated memory controller and PCI Express 2.0 interface. The second benefit is performance. Turbo Boost helps to elevate LGA 1156-based parts to Core i7-900-class performance levels in certain applications. Both benefits became obvious in our article, Intel’s Mainstream Magnum Opus.
Performance Increase Where It's Needed
The current generation of Turbo Boost accelerates a single core by four 133 MHz increments (or bins) in the case of Core i5-700-series and by as many as five increments for the Core i7-800-series. This equals clock speed bumps of 533 and 667 MHz. Two cores can accelerate by four clock speed increments, while three and four cores still may receive a simultaneous 133 MHz boost (up to 266 MHz for the top model Core i7-860). Obviously, the new chips operate with higher power consumption every time Turbo Boost kicks in, though they're kept under a 95W ceiling by Intel's on-die Power Control Unit.
Power Down?
We want to answer some basic questions: What is the real reduction in system power consumption compared to Core 2 Quad platforms? What is the efficiency (performance per watt) for the new LGA 1156 generation? What’s the difference in efficiency for a LGA 1156 system with and without Turbo Boost enabled?
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will they ever make LGA 1156 mother boards with 2 x pci-2 x16? it would make these new cpus so much more attractive for gamers that want a more efficient pc.
i meant pci-e* no post edit=ftl
its nice to have all these new components with high efficiency power. SSD, core i5/i7 cpus, HD 5800s GPUs, even powerful machines can be green for everyday use (e-mail, a/v streams, etc)
to avoid the cannibalization of x58s, the chance of those are very slim, especially if intel can't sell you 2 600 dollar GPUs
They already have, go have alook at the top of line EVGA P55 boards, they support 2x PCIe @ 16x speed because added a NF200 chip to them.
MiamiU have alook at the top of the line EVGA P55 boards, they have added the NF200 chip to them, allowing for 2x PCIe @ 16x bus speed.
will they ever make LGA 1156 mother boards with 2 x pci-2 x16? it would make these new cpus so much more attractive for gamers that want a more efficient pc.
Remember that the VGA PCI-e controller in on the Lynnfield CPU itself and not on the motherboard chipset. No LGA 1156 chipset will ever have a PCI-e controller for GPU.
The PCI-e controller on Lynnfield CPU is 1x16/x4 or 2 x8/x8.
As for Multi CPU scaling in x8/x8 mode vs x16/x16 mode, it is usually 2% slower in framerates, but nothing more. Remember, Lynnfield is the cheaper alternative to X58 Nehalems because of the cheaper motherboard chipset (lacks PCI-e controller for VGA) and Dual Channel DDR3 vs Triple Channel DDR3.
http://techreport.com/articles.x/17513/8
Oh, there are some spelling mistakes, in the above post
Also look at this Lynnfield/Bloomfield bench - In some newer games x16/x16 makes quite the difference
http://www.anandtech.com/cpuchipse [...] i=3634&p=9
Ohh, Foxconn and ASUS (and EVGA) apparently have a solution for x16/x16, but these boards are $220+
Reading it now, thanks for this, as its been asked by us, the readers, and once again Toms comes thru, with the help of great writing/fact finding and benching.
will they ever make LGA 1156 mother boards with 2 x pci-2 x16? it would make these new cpus so much more attractive for gamers that want a more efficient pc.
Why should they? x8/x8 is shown to be just as fast as x16/x16 so long as you a good PCI-ex controller (p55 has an excellent controller but on some P45 boards Crossfire isn't that great due to controller issues). Read Toms review on the HD5850, it shows Lynnfield didn't bottleneck Crossfire performance.
At the moment there is no need to add more lanes and by adding more lanes it will only further increase the cost of an already costly P55/LGA1156 setup.
Ummmmmm Where did you see it for that price? --- The cheapest I can find it is $350 at Newegg.
The conclusion that turbo is not that efficient is not completely accurate. The total wattage used for a job with turbo might actually be lower because the higher speed will get the job done in less time, therefore keeping the cpu at high power usage for less time.
There are a couple of flaws in this test setup in my mind. Testing the new i5/i7's against the Core 2 Quad S series is a bit of a apples to oranges. No one bought the S series unless they were making an HTPC. The Core 2 Quad Extreme also, as the name implies, isn't mainstream either. The article would have been better served using the Core 2 Quad 9550 and maybe even AMD's Phenom 965. Also, no one is buying the i7 870. The i7 860 is much more mainstream. These are more realistic buys.
X2 jblack. Waaaaaaaay off calling the 9550s a $199 processor. Even the regular non-s version is going for $269 on newegg.
Am I missing something obvious here?
Wouldn't Vantage be at least partially GPU-dependent as well?
Meaning that the power-efficiency discussion isn't entirely accurate as the test run-time isn't wholly dependent on the CPU horsepower.
I might be wrong of course but I'd rather see something like a Prime95 run for a static number of loops with 1, 2, 4 and 8 threads as an alternate comparison. Vantage would, in my mind at least, be dependent on too many different aspects of the computer hardware platform to be used for what should be a strict CPU-comparison.
Well that's my 2c anyway. Feel free to correct me.
I guess these results aren't that surprising; we've known for quite some time now that moderate overclocking doesn't actually do much for power efficiency, and Turbo mode does exactly that: overclock the processor while staying within the TDP envelope (although I'm not sure if overvolting is involved as well).
Still, I conjecture that perhaps limited overclocking might actually increase efficiency by a little; maybe around the 266MHz mark (again, just a conjecture). This is the kind of clock speed gain we might see with two or three cores active.
For this reason alone I do agree with Exodite2 to some extent that benchmarks with applications known to be moderately multithreaded would be interesting. Even if they are not particularly useful in describing typical power efficiency numbers, they certainly contribute to our understanding of Turbo's impact on power efficiency.
And yes, please do run this test on the i7-860, I believe that is the processor of choice for a budget-conscious Lynnfield-i7 buyer, after all. Looking forward to additional analysis
The conclusion that turbo is not that efficient is not completely accurate. The total wattage used for a job with turbo might actually be lower because the higher speed will get the job done in less time, therefore keeping the cpu at high power usage for less time.
Wasn't the total wattage already measured in this graph and shown to be higher with Turbo enabled? (At least, just for the i7-870, and only for PCMark.)
It makes sense, because Turbo is basically overclocking.
What about the effect of hyper-threading?
Would like to have seen the AMD 785G board and Athlon II X4 CPU with the same equipment (GTX 260) thrown into the mix just for results. The AMD 785G and the Athlon II x4 are both fairly efficient and beat on price big time.
Would like to have seen the AMD 785G board and Athlon II X4 CPU with the same equipment (GTX 260) thrown into the mix just for results. The AMD 785G and the Athlon II x4 are both fairly efficient and beat on price big time.
Athlon II is designed to counter i3, not i5. PII vs. i5 make more sense.
BTW, since i3 will have PCI-express lane and graphics on chip, it will be the most efficient desktop setup by far. Athlon II X4's die will be huge next to the 32 nm Clarkdale i3 which is "quad" core with hyper-threading.
Well I would say the i5 is certainly a leap in the right direction!!!