Intel’s Second-Gen Core CPUs: The Sandy Bridge Review

The System Agent And Turbo Boost 2.0

The System Agent

Altered principally in name, the system agent includes functionality previously associated with the uncore—that is, it includes the processor subsystems that can’t be grouped with the execution cores (and now the graphics engine, too).

In that list, you  have the dual-channel memory controller (which officially supports transfer rates of up to 1333 MT/s), 16 lanes of second-generation PCI Express connectivity, the DMI, and a more advanced power control unit, responsible for managing the operation of Turbo Boost, among its other roles.

Turbo Boost 2.0?

Speaking of Turbo Boost, Sandy Bridge includes a second-generation implementation of this technology, first seen two years ago on Bloomfield-based Core i7-900-series chips, but really only throttled up, so to speak, on Lynnfield a year later.

The premise behind what I’ll call Turbo Boost 1.0 was that, in a multi-core CPU, available resources are not always in use. An application like iTunes, for instance, can only use one core at a time. And yet, the chip’s thermal ceiling is defined by a worst-case scenario of all cores fully-utilized. Turbo Boost takes advantage of the thermal headroom that exists when the chip executes a workload like iTunes, in turn accelerating the one active core to get its task completed faster.

Turbo Boost 1.0 is smart in that it dynamically ratchets up the frequency of active cores based on temperature, current, power consumption, and operating system states. But it won’t exceed programmed power limits, even if thermal headroom exists to push performance harder.

In the real-world, a processor doesn’t heat up right away, though. From idle, it takes time to reach its thermal ceiling. Turbo Boost 2.0 (or next-gen Turbo Boost, whatever you want to call it) allows the processor to exceed its power ceiling until it reaches its thermal limit, at which point it drops power to conform to those same programmed limits.

Turbo Boost 2.0 does not mean the CPU will exceed its maximum Turbo Boost frequency. If you have a Core i7-2600K with a 3.4 GHz base clock and 3.8 GHz maximum Turbo clock, 3.8 is as fast as it’ll go in its stock trim. It’ll simply stay there longer—until the CPU heats up to its thermal limit—before backing down.

Unfortunately, it’s not really possible to quantify the benefits of this capability. The best I could get out of Intel was that it helped improve responsiveness. On the desktop, I frankly wasn’t able to tell a difference, and as a result, Turbo Boost 2.0 comes across somewhat gimmicky.

To be fair, it’s going to mean more in the mobile space, where base clocks start off a lot lower to save power, and Turbo Boost ceilings scale significantly higher. We have a Sandy Bridge-based notebook in the office and will be putting it through its pages this month, too.

Also more impactful in the mobile space is Sandy Bridge’s ability to share thermal budget between graphics and processor cores. Previous-generation Arrandale cores were able to do this, applying the Turbo Boost concept to both components. Now Sandy Bridge enables the same capability on the desktop. Intel says that, in 3D-heavy workloads, the power control unit will bias to the graphics core, as it stands to improve performance more than faster CPU cores.

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  • JE_D
    BENCHIES! Thanks Tomshardware!
  • Editor, page 10 has mistakes. Its LGA1155, not LGA1555.
  • cangelini
    MoneyFace pEditor, page 10 has mistakes. Its LGA1155, not LGA1555.

    Fixed, thanks Money!
  • juncture
    "an unlocked Sandy Bridge chip for $11 extra is actually pretty damn sexy."

    i think the author's saying he's a sexually active cyberphile
  • cangelini
    juncturei think the author's saying he's sexually active

    Just this.
  • fakie
    Contest is limited to residents of the USA (excluding Rhode Island) 18 years of age and older.

    Everytime there's a new contest, I see this line. =(
  • englandr753
    Great article guys. Glad to see you got your hands on those beauties. I look forward to you doing the same type of review with bulldozer. =D
  • joytech22
    Wow Intel owns when it came to converting video, beating out much faster dedicated solutions, which was strange but still awesome.

    I don't know how AMD's going to fare but i hope their new architecture will at least compete with these CPU's, because for a few years now AMD has been at least a generation worth of speed behind Intel.

    Also Intel's IGP's are finally gaining some ground in the games department.
  • cangelini
    fakieContest is limited to residents of the USA (excluding Rhode Island) 18 years of age and older.Everytime there's a new contest, I see this line. =(

    I really wish this weren't the case fakie--and I'm very sorry it is. We're unfortunately subject to the will of the finance folks and the government, who make it hard to give things away without significant tax ramifications. I know that's of little consolation, but that's the reason :(

  • LuckyDucky7
    "It’s the value-oriented buyers with processor budgets between $100 and $150 (where AMD offers some of its best deals) who get screwed."

    I believe that says it all. Sorry, Intel, your new architecture may be excellent, but unless the i3-2100 series outperforms anything AMD can offer at the same price range WHILE OVERCLOCKED, you will see none of my desktop dollars.

    That is all.
  • DjEaZy
    ... will wait til 'buldozer'... and two things may happen... the buldozer at the price point will kick ass... or the sandy bridge parts will get cheaper...
  • touchdowntexas13
    There is some pretty cool stuff going on here. I like the way the article points out the good and the bad. As for me I really am mystified at Intel's decision to only put the higher end graphics in the k-models as most likely anyone buying them will be going for the P67 platform that doesn't even use the integrated graphics. It would have been soooo much better for the HTPC crowd if there were some lower end chips with the better integrated graphics. I guess somehow this is money motivated???

    As for overclocking, well it seems a bit odd in the way it is being implemented. But for $216, I can't complain too much about a quad-core with a base clock of 3.3 GHz. Some enthusiasts won't like the limited overclocking features, but others will welcome the simplified approach.

    I will be building my brother a new gaming computer for graduation this summer and now I have another viable option to look at. I had planned on going with a P55 + i5 760, but now I will need to consider the P67 + i5 2500K.

    Waiting on bulldozer...
  • jyar727
    I mean this looks like a thorough test but its really not. I wanted to see an I7 1:1 clock performance comparisons. Mainly, 3.4GHz I7-950 vs 3.4GHz I7-2600K. Obviously 3.4 GHz new tech would usually beat a 3.0 current tech in benches. UGH. lame lame lame. Really want to see this comparison instead.
  • silversurfernhs
    Shouldn't the title be second gen Core i series... because Core 2s were second gen Cores, weren't they?
  • Tamz_msc
    Where is the 980x in these benchmarks?
    Other than that its a great article, and I'm drooling over QuickSync!
  • Maziar
    Thanks for the review Chris :)
    QuickSync definitely looks interesting.
  • Ramar
    I just bought an i5-760 system on 12/30 from newegg, I guess I wasn't paying attention to when Sandy Bridge would actually be released. It's not here yet, so I could just send the mobo and cpu back when they get here, but I don't see enough justification as a gamer to move to the 2500k. Based on the number of 1.35V 4.7ghz for the 2600k, I would assume that on stock voltage it doesn't get much higher in frequency than my 760 will, and I don't like raising stock voltage.

    This is all very nice, but I'll keep my bclk control for now and maybe move up when I get out of college in seven months and the tech is set in stone and dropping in price a little.

    Not a bad chip, and I'm excited to see where they go with it. =]
  • Hellbound
    Is sandy bridge the replacement to the x58 chipset? I thought I read somewhere they were planning on x68 sometime in 2011.
  • djdarko321
    Remember though as this is the lower end Sandy Bridge platform NOT THE MAIN LGA2011 socket. As Intel decided to release for the mainstream first before the enthusiasts this go around.
  • Tamz_msc
    Just looked at the AnandTech review and here is their opinion -

    In all but the heaviest threaded applications, Sandy Bridge is the fastest chip on the block—and you get the performance at a fairly reasonable price. The Core i7-2600K is tempting at $317 but the Core i5-2500K is absolutely a steal at $216. You're getting nearly $999 worth of performance at roughly a quarter of the cost.

    These things are as fast as the i7 980X and in some cases they're even faster!
  • swiftor
    i5-2500k + p67 ftw!
  • nekromobo
    What if you throw something like 8k x 4k or 4k X 4k resolution video to QuickSand.. Sync :)

    Nice review, but personally still not going to replace my 3.6ghz C2Quad.. when will this cpu die so I can replace it!
  • Shuge1
    Im just waiting for bulldozer to get me out of buyin the i5 2500k
  • Reynod
    Quick Synch is just downright embarrasing for AMD ...