Core i7-2820QM: Sandy Bridge Shines In Notebooks

Meet Sandy Bridge's True Purpose

Today's desktop replacements deliver a ridiculous amount of performance compared to the mobile flagships we've seen in the past. But these powerhouses come with a trade-off, other than their hefty price tags. You see, there is an unbreakable relationship between compute horsepower and power consumption.

On the desktop, processors based on Intel's Sandy Bridge architecture top out at 95 W. This is a significant improvement over the 130 W Bloomfield design, manufactured at 45 nm, since performance is higher in many cases. Nevertheless, it's still not realistic to use desktop-class CPUs in notebook shells and expect them to last very long on battery power. Then again, most of the folks who buy DTRs don't really care about keeping away from wall sockets. They're more interested in using those machines as workstations that transport easily from one power plug to the next. In that case, a larger form factor is fine and dandy.

To be fair, Bloomfield was never intended for notebooks. Neither was Lynnfield. The true first-generation Nehalem-based CPU aimed at the mobile space was Clarksfield. The second-generation that followed was Arrandale.

At the high end of the mobile space, Clarksfield kicks butt. You just need to take a peek under the hood of any DTR from a major system vendor. It is almost always a Clarksfield-based processor. There's a good reason behind this. Transitioning from the Core microarchitecture to Nehalem was a really big deal, both in terms of what it did for potential performance and power management. Truly, Nehalem-based mobile processors can go toe-to-toe with their desktop big brothers (if you don't believe us, read Thomas' coverage of the Clevo X1800).

Sandy Bridge Mobile: Core i7 At 55 W/45 W

Intel continues to use the Core i7, Core i5, and Core i3 brands, suggesting good, better, and best. While we're still not sure that this is superior to what it had going with Centrino (now the designator for the company's wireless radio), we'll admit that the trio of Core brands is much better than AMD's attempt at marketing with Vision.

From an architectural standpoint, the mobile Core i7-2920XM and -2820QM are closely related to the desktop Core i7-2600K. With a smaller last-level cache and slower maximum graphic clock, the Core i7-2720QM and -2630QM fall somewhere between the Core i7-2600K and i5-2500K. Just keep in mind that the -2500K doesn't have the benefit of Hyper-Threading, so it's limited to 4C/4T. Meanwhile, all of Intel's new mobile CPUs feature Hyper-Threading support.

Swipe to scroll horizontally
Header Cell - Column 0 i7-2920XMi7-2820QMi7-2720QMi7-2630QM
Core  / Threads4 / 84 / 84 / 84 / 8
Base Clock2.5 GHz2.3 GHz2.2 GHz2.0 GHz
Max. Turbo Clock3.5 GHz3.4 GHz3.3 GHz2.9 GHz
Memory (MT/s)1333133313331333
L3 Cache8866
HD Graphics3000300030003000
Max. Graphics Clock1300 MHz1300 MHz1300 MHz1100 MHz
AVX SupportYesYesYesYes
Quick Sync SupportYesYesYesYes
AES-NI SupportYesYesYesNo

As with the desktop models introduced earlier this month, Intel's mobile lineup also uses the digit '2' in front of each model to indicate membership in its second-generation Core CPU club. The 2 makes sense to us. But the three numbers that follow are arbitrary performance indicators—exactly what you grew accustomed to from the Nehalem-era CPUs. Intel uses clock rate, L3 cache, Hyper-Threading, and Turbo Boost to differentiate one model from another. It’s a safe guess, though, that -2920QM is faster than -2820QM, and so on.

You'll notice that Intel maintains the TDP profile of its previous mobile offerings. For its SV (standard voltage) Core i7s, the company keeps the limit at 55 W, which we saw with the Core i7-920XM.

The 2.3 GHz Core i7-2820XM enjoys up to eleven bins of Turbo Boost acceleration, running at a maximum frequency of 3.4 GHz in single-threaded applications. With two cores active, it drops to 3.3 GHz. And with all four working, the CPU drops to 3.1 GHz. Comparatively, the desktop Core i5-2500K starts out with a base clock at 3.3 GHz and employs four bins of Turbo Boost to get to 3.7 GHz.

The 2.5 GHz Core i7-2920QM runs as fast as 3.5 GHz in single-threaded apps, and the 2.2 GHz Core i7-2720QM clocks up to 3.3 GHz. While all mobile Core i7s include Hyper-Threading, only the top two SKUs feature an 8 MB L3 cache. The other two mobile Core i7s in Intel's 55/45 W stable are limited to 6 MB.

  • cmartin011
    Second!!! really a thousand dollars for a mobile cpu
  • one-shot
    What are the numbers for battery life for idle, surfing the web, and watching HD video? Several reputable sites have posted up numbers and I'm not seeing a chart that states these numbers, just lots of performance numbers to reiterate the obvious that it's more powerful and more efficient than Arrandale CPUs.
  • acku
    This isn't a production notebook so battery life pertaining to this specific notebook is rather pointless in relation to other models. There are other factors at play: LCD panel, battery density, etc... However, platform power consumption numbers are posted on the second to last and last page.

  • one-shot
    ackuThis isn't a production notebook so battery life pertaining to this specific notebook is rather pointless in relation to other models. There are other factors at play: LCD panel, battery density, etc... However, platform power consumption numbers are posted on the second to last and last page.AndrewTomsHardware
    That isn't what I was looking for. On Anandtech and Tech Report, a Compal notebook with a Core i7 2820QM achieved between six and seven hours of battery life when web browsing. I was looking for a comparison to help me make a more informed decision.

    Something like these is what I was referring to.

    Battery life is not pointless in any way. A pre-production model or not, it's relevant. If helps give us, the consumers, a better perspective to how laptops with these CPUs will perform with regards to battery life.

    I'm surprised it wasn't included.
  • acku
    Fair point and I completely agree that battery life is not pointless. But on our point, we did go over power as far as browsing and Flash video if you read our conclusion.

    On an platform level, you can expect a new Sandy Bridge Core i7 to achieve roughly double the battery life of a notebook with an Arrandale Core i5.

    What I disliked about the previous benchmarks (including the ones you referenced) was that they automatically handicapped the benchmark against the Sandy Bridge mobile platform. Forget the whole DTR argument. A 17.3" panel will generally consume more power than a 15.6" (Look at the notebooks it was compared against.) When you isolate it down to the platform level then you can say all-else-being-equal (LCD, hard drive, wireless card, etc...), a notebook based on a Sandy Bridge mobile processor will ~ double battery life. Those other sites showed a roughly 33% improvement because of the other variables at play.

    Remember though that when you are talking about H.264 playback, this is all run through the hardware decoder. You are getting very little battery burn no matter what hardware you are running. What really matters then is the total platforms power consumption and the density of your battery (2.6AH vs 2.9AH cells).

    But back to your main point, if that is what you want to see on a DTR, then we will include it next time. Frankly, I'm more interested in the battery life of non-DTR mobile CPUs. "Normally" people don't care about battery life on a 17.3" mobile workstation.
  • bearclaw99
    Damnnnnn...those are some amazing benches for a laptop CPU. Beats some of the desktop i7s and probably all of AMDs desktop chips
  • SteelCity1981
    If AMD is paying attention, it needs to get its act in order. Brazos is one step up from being a pawn in the AMD Fusion chess set.

    AMD's Brazos platform is very impressive especially the E-350 series that's paired with an Radeon HD 6310 in gaming performance. Soo impressive in fact that the gaming performance rivals that of Core i5 661 in a lot of games and even goes toe to toe with the Core i5 2500k in some games like Call OF Duty Black Ops! As show here....
  • _Pez_
    amd is losing ground.. they are taking too long releasing new products.. Intel is expensive.. damm!
  • hardcore_gamer
    I think bulldozer will be able to compete in terms of TDP because of the two integer units / core
  • Vadim_79
    I just bought myself an Asus N53SV a couple of days ago, so far it's been great, it can handle any game i throw at it due to the combined intel 3000 and gf540m. Whenever i use the notebook for things like surfing the web it uses the intel 3000, so i get better battery life. I game with the notebook plugged in and set to maximum performance on a 42 inch plasma through hdmi. And it beats my desktop as far as framerates are concerned