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Efficiency Features On-Board

Efficiency Comparison: Sandy Bridge Vs. Intel And AMD CPUs
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There is a lot to tell about Sandy Bridge when it comes to power and efficiency. Although this is the first Intel consumer processor that fully integrates a graphics unit with the processor die, the architecture was in fact built to be very modular, despite the high level of integration.

All Sandy Bridge CPUs are split into three sections, which equal three individual power and frequency domains. One is the System Agent, which includes the memory controller and PCI Express, the other contains the cores with shared L3 cache (now called the last level cache) and the ring bus architecture, and the third one is the graphics unit. Each of these units is scalable as well, meaning that six or eight cores (instead of two or four) are already planned on higher-end platforms.

Flexible TDP Usage

A key to high power efficiency is Sandy Bridge’s ability to have each of these CPU sections utilize large portions of the thermal and the power envelopes when needed and if possible, while the others may be switched into a lower power state. No other platform currently shows such a significant difference between idle power and peak load power. Let me give you an example. The Core i7-2600K system with processor graphics requires only 32 W at idle, but jumps to 136 W once we switch on Prime95. This is a 4.25x jump in system power consumption. If we imagine a dual-socket, eight-core system subject to the same increase, this power jump would result in pretty incredible numbers. Lastly, let’s recall that not only the cores, but also the graphics unit, has a dynamic frequency range that can reach 1100 MHz on Core i5 and up to 1350 MHz on Core i7.

Turbo Boost 2.0

One of the key features that helps improve overall efficiency, linked closely to TDP utilization, is the second-generation Turbo Boost technology. Depending on the processor model, it triggers a temporary increase of core clock speeds (up to the maximum Turbo Boost frequency) if there is significant load. Different from earlier implementations, Turbo Boost 2.0 can involve all available cores, and it will increase the clock speed for as long as the thermal and power envelopes aren’t fully utilized. In real-life, this means that a Sandy Bridge-based Core i5 or i7 will run at increased clock speed for a limited period of time. When the maximum thermal power is reached, the processor will reduce the clock speed until power and clock speed even out--in a worst case this is the processor’s rated clock speed.

Turbo Boost alone does not necessarily increase efficiency, but a system that is as low in idle power as the Sandy Bridge generation should stay in such a low power state as long as possible. This means that it should tackle pending workloads as quickly as possible, so it can return to this state quickly.

Modern 32 nm Manufacturing

Although this is not an efficiency-oriented feature by itself, the 32 nm manufacturing process is definitely a key enabler for maximum performance per watt. Smaller gates and transistors translate into lower operating voltage and less power consumption. Eventually, this allows for Intel to flexibly utilize the transistor budget and area in a smart manner. This is where the paradigm change is happening: simply adding cores resembles a brute force approach, which is similar to cranking up clock speeds. It will increase power consumption and eventually it will not scale linearly. We know for a fact that, given the threading optimizations available in software today, eight cores will not provide twice the performance of four cores. However, power consumption will be more than 2x higher. As a result, Intel's engineers had to put a lot of thought into determining the functions they wanted to accelerate in hardware, implementing improvements as efficiently as possible while maintaining or minimizing power consumption. The trick is not to just improve performance per unit of power, but also to consider performance per square millimeter.

Cool and Really Cool

The Intel briefing documents on Sandy Bridge describe features that the company calls either cool or really cool. A lot of the optimization efforts for Sandy Bridge went into finding microarchitecture enhancements that provide a better-than-linear improvement in performance/power. A ‘cool’ feature translates to improving performance, while keeping the corresponding increase in power consumption at a linear level, as a worst-case. Ideally, power consumption should increase less than performance.

A ‘really cool’ feature has an even more significant impact, as it gains performance while actually reducing power consumption. This applies to the upgraded branch predictor paired with the decoded µops cache, which allows the decoders to stay off more often. All other core improvements are referred to as cool.

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  • 5 Hide
    unlicensedhitman , January 4, 2011 5:47 AM
    Very good late night read :p 
  • 8 Hide
    gomi , January 4, 2011 5:51 AM
    AMD has some serious catching up to do! I hope bulldozer can keep it competitive!
  • 4 Hide
    jprahman , January 4, 2011 6:00 AM
    Wow, Sandy Bridge 50% faster on average with 50% less power draw than the Phenom II X4's and X6's. AMD really needs to deliver with BD, offering performance that is close, but at a lower price point.
  • 4 Hide
    joytech22 , January 4, 2011 6:12 AM
    AMD better step up their game because these results are worrying.

    If AMD don't deliver this year I'm straight for Intel.
  • -1 Hide
    fstrthnu , January 4, 2011 6:34 AM
    Looks like AMD better use their last lifeline (Bulldozer) well; otherwise, it's off to the races for Intel. By now, there's no way AMD's ever going to catch up to Intel (since they're already behind now, and Intel's going to be even further ahead by the time Bulldozer's out)
  • 3 Hide
    Reynod , January 4, 2011 6:34 AM
    Bulldozers new cores will not see a significant IPC improvement to allow it to come anywhere near SB, so AMD's major drawcard still remains in the low end of the market with fuzion products delivering a better quality IGP (on die) than SB ... albeit, from the previous article and anandtech's tests, SB has a pretty good alternative with the 3000 series graphics core.

    SB also has a ULP version which will compete with Fuzion, a faster cpu and a comparable GPU solution, so Intel are not leaving the portable end of the market to AMD either.

    AMD's focus on real cores whilst commendable, isn't a serious competitor to Intel now they have a much faster, wider executing processor, running on a smaller, cooler, more cost effective process.

    AMD would have to pull three cats of of the bag to come near to catching up ... I don't see that happening.

    I mentioned previously about AMD's ability to make better use of the GPU ondie, to do things like encoding and decoding, and Intels fast response hase been the Quick synch engine. Note this only works if you have the IGP enabled, but it delivers. AMD has not been able to respond again ... when this is an area they have expertise.

    I see AMD's stock starting to plummet one these start volume production, as they have no real market niche to retreat to ... other than "value" ... at the very real loss of profits as a consequence.

    Where is NVidia in all of this?

    Quite frankly they are gone ... unless the company shrinks to "boutique" level, trying to compete with AMD on high end discrete graphics. No chipset market, and Tegra2 chews too much power.

    Intel will rise now to the point where all opposition is likely to be crushed into oblivion.

    That's not a nice place to be when your a consumer.

    Ask the electronics and car industries what it is like to be held to ransom by the Chinese rare earth mines ...
  • 4 Hide
    mosox , January 4, 2011 6:39 AM
    Nice but why the i5-750 and not the 760?

    I'd rather want to see the $100-$150 chips. For a regular user on a budget those are much more interesting -> cheaper CPU = more $$ for a better video card. Who cares about 10 seconds/minute, when encoding or archiving, really? Not me.

    Cheap quads and cheap good mobos, that's what we need, Intel. Also the ability to replace our dual/quad with a 6 or 8 core CPU on the same mobo.
  • 1 Hide
    andrewcutter , January 4, 2011 6:39 AM
    in the test system page, the lga 1155 platform has lga 1156 processor :D 
  • 1 Hide
    Anonymous , January 4, 2011 7:33 AM
    There should be a comparison between Intel Sandy Bridge vs AMD Fusion.
  • 1 Hide
    chovav , January 4, 2011 7:48 AM
    Was that the standard Intel cooler you were using on the SB platform? and if you'll use a (good) after-market cooler , will the turbo boost stay on continually? Did you check what clock rates the cores were at with the multi-threaded applications?

    ...and what about overclocking SB? why haven't we seen anything about that?


    great article for the rest, its amazing to see that Intel has twice the efficiency score of AMD..
  • 1 Hide
    Tamz_msc , January 4, 2011 9:11 AM
    Eagerly awaiting some overclocking articles!
  • 3 Hide
    JimmiG , January 4, 2011 9:20 AM
    AMD's current architecture isn't really bad, it's just outdated. They just haven't done enough from K7 (1999) to K10.5. So BD really needs to be quite radical.

    I'm still hoping BD will be competitive. If not, CPUs that cost "only" $999 will be considered cheap, while performance of low-end and mid-range CPUs would stagnate at current levels. No need to lower your profit margins and bring out something faster when there's no competition. Maybe a small speed bump every couple of years to make people upgrade, but they'd essentially only be competing against themselves.
  • 1 Hide
    vaughn2k , January 4, 2011 9:44 AM
    Waiting for 'Zacate' Bench... before I decide...
  • 0 Hide
    christop , January 4, 2011 10:36 AM
    nice..
  • -1 Hide
    jasonpwns , January 4, 2011 11:04 AM
    reynodBulldozers new cores will not see a significant IPC improvement to allow it to come anywhere near SB, so AMD's major drawcard still remains in the low end of the market with fuzion products delivering a better quality IGP (on die) than SB ... albeit, from the previous article and anandtech's tests, SB has a pretty good alternative with the 3000 series graphics core.SB also has a ULP version which will compete with Fuzion, a faster cpu and a comparable GPU solution, so Intel are not leaving the portable end of the market to AMD either.AMD's focus on real cores whilst commendable, isn't a serious competitor to Intel now they have a much faster, wider executing processor, running on a smaller, cooler, more cost effective process.AMD would have to pull three cats of of the bag to come near to catching up ... I don't see that happening.I mentioned previously about AMD's ability to make better use of the GPU ondie, to do things like encoding and decoding, and Intels fast response hase been the Quick synch engine. Note this only works if you have the IGP enabled, but it delivers. AMD has not been able to respond again ... when this is an area they have expertise.I see AMD's stock starting to plummet one these start volume production, as they have no real market niche to retreat to ... other than "value" ... at the very real loss of profits as a consequence.Where is NVidia in all of this?Quite frankly they are gone ... unless the company shrinks to "boutique" level, trying to compete with AMD on high end discrete graphics. No chipset market, and Tegra2 chews too much power.Intel will rise now to the point where all opposition is likely to be crushed into oblivion.That's not a nice place to be when your a consumer.Ask the electronics and car industries what it is like to be held to ransom by the Chinese rare earth mines ...


    Quite frankly I will be buying a bulldozer chip. My athlon ii x4 has done what it needed to and I am a gamer so therefore AMD still has me as a customer. I am also a Nvidia customer (so basically I get screwed in terms f sli) If you think Nvidia is close to dead then you really are ignorant. Also bulldozer low wattage chips consume very little power consumption same with the gaming chips. All I am going to say wait for bulldozer before you speak.
  • 1 Hide
    hannibal , January 4, 2011 11:12 AM
    AMD don't have enough money to compete in production technology...
    If AMD would make SP "copy" with their factories in 45nm production technology, it would not be so good CPU, because Intel has better production technology at this moment.

    Hard situation for customers indeed... I still remember time when Intel CPU's were very expensive because of no/little competition...
    AMD needs to have good 32nm transition and good architecture upgrade (bulldoser) at the same time. Hard trick to do (Intell do it one step at time / tick tock...), but I really hope that AMD can do it. In gpu part there should not be problem. SB GPU is not so impressive, but if Intel production technology allow faster clockspeed in smaller space, even superior GPU technology would in trouble.
    I will kept my fingers crossed that AMD pulls the rabbit out of the hat and bulldoser cause some sweat to Intel. It would be more than healthy!
  • -1 Hide
    Wheat_Thins , January 4, 2011 11:20 AM
    jasonpwnsQuite frankly I will be buying a bulldozer chip. My athlon ii x4 has done what it needed to and I am a gamer so therefore AMD still has me as a customer. I am also a Nvidia customer (so basically I get screwed in terms f sli) If you think Nvidia is close to dead then you really are ignorant. Also bulldozer low wattage chips consume very little power consumption same with the gaming chips. All I am going to say wait for bulldozer before you speak.


    So you're going to buy a bulldozer regardless even if Intel wipes the floor with it? Fanboy to the core?
  • 3 Hide
    johntmosher , January 4, 2011 11:34 AM
    Why don't you include the i7 980x in the benchmarks?
  • 1 Hide
    gamerk316 , January 4, 2011 11:38 AM
    Ouch. The trashing continues...
  • -1 Hide
    jasonpwns , January 4, 2011 11:41 AM
    hannibalAMD don't have enough money to compete in production technology...If AMD would make SP "copy" with their factories in 45nm production technology, it would not be so good CPU.Hard situration for customers indeed... I still remember time when Intel CPU's were very expensive because of no/little competition... AMD needs to have good 32nm transition and good architecture upgrade (bulldoser) at the same time. Hard trick to do (Intell do it one step at time tick tock...), but I really hope that AMD can do it. In gpu part there should not be problem. SB GPU is not so impressive, but if Intel production technology allow faster clockspeed in smaller space, even superior GPU technology would in trouble.I will kept my fingers crossed that AMD pulls the rabbit out of the hat and bulldoser cause some sweat to Intel. It would be more than healthy!


    The reason for this is everyone even gamers (sheesh) think that 3 frames is going to make such a big difference. My athlon ii x4 paired with a gtx260 runs all the games I want on High/Max with 4x AA with a resolution of 1366x768. I am sure it could take on higher ones. In games there is little to no difference in frames between AMD/Intel CPU's only a bigger price tag.
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