Core i7: Running The Gamut
In the past, Intel has used a handful of modifiers to further distinguish its model numbers: M, LM, UM, QM, and XM. There aren't any unlocked mobile processors, as overclocking generally isn't something power-conscious notebook users wish to inflict upon their batteries. This explains the lack of K-series SKUs on the mobile side.
Expectantly, M is the primary designator signaling the difference from mobile and desktop products. There are additional mobile offerings that substitute an E for M, which is a further subset of the mobile product line that indicates embedded processor packages. Everything else is pretty straightforward: L for Low Voltage, U for Ultra Low Voltage, Q for Quad-Core, and X for Extreme Quad-Core.
Today, we are looking at a fairly beefy selection of mobile Core i7s. If the performance of the desktop parts is any indicator, this is an exciting prospect. We are talking about some serious processing power at ultra-low and low-voltage power profiles.
As an aside, if you look at the whole Sandy Bridge mobile lineup, you will notice a lack of L- and U-designated processors. This can be explained away by the last digit of the model name. Models that end with 9 indicate LV parts, while 7 is for ULV. This is somewhat of a departure from the company's previous mobile scale.
|Core / Threads||2 / 4||2 / 4||2 / 4||2 / 4||2 / 4|
|Base Clock||2.7 GHz||2.3 GHz||2.1 GHz||1.6 GHz||1.5 GHz|
|Max. Turbo Clock||3.4 GHz||3.2 GHz||3.0 GHz||2.7 GHz||2.6 GHz|
|Max. Graphics Clock||1300 MHz||1100 MHz||1100 MHz||1000 MHz||950 MHz|
|Quick Sync Support||Yes||Yes||Yes||Yes||Yes|
As we noted in our launch coverage, there are actually three different versions of the Sandy Bridge die shipping at launch. The quad-core configuration—the one composed of 995 million transistors—measures 216 mm². Then, there’s a dual-core die with 12 execution units making up its graphics engine. That one features 624 million transistors on a 149 mm² die. Finally, the slimmest variation sports two cores and a graphics engine composed of six EUs. You're won't see that last version represented in Intel's current mobile lineup, since the complete portfolio is made up of dual- and quad-core CPUs with HD Graphics 3000. Moreover, all of the mobile CPUs enjoy Hyper-Threading support, a benefit missing from about half of the desktop line, including our recommended i5-2500K.
|Die Size (square mm)||Transistors (million)|
|Sandy Bridge (4C)||216||995|
|Sandy Bridge (2C, HD Graphics 3000)||149||624|
|Sandy Bridge (2C, HD Graphics 2000) - Desktop Only||131||504|
|Lynnfield and Clarksfield (4C)||296||774|
|Westmere and Arrandale (2C)||81||383|
Another difference is the introduction of another new interface. The mobile world doesn't have the same issues to worry about as desktop PC. So, although its second-gen Core CPUs share a similar architecture, they employ dissimilar processor interfaces. The new Core i7 Mobile CPUs drop into an rPGA 988 socket, which is one pin short of the mPGA 989 seen on the previous Clarkdale-based i7s. That's right; Intel is breaking compatibility with its first-gen Core chips on the mobile side, just as it did on the desktop. Fortunately, processor upgrades are less prevalent in notebooks, so this move should affect enthusiasts far less.
And whereas the desktop chips are pinless, mobile Core i7s actually wear the pins in this relationship. Though, we should point out that we haven't even listed all variations of the mobile Core i7s. The ---9M (LV) and ---7M (ULV) parts come in BGA 1023, while the 55 W and 45 W also come in a BGA 1224 package. If that doesn't make things confusing, other models end in ---5. This seems to be the only differentiation between BGA and rPGA specific packages.
Everything in the architecture and technical details that we explained in our launch coverage of Sandy Bridge also applies to the mobile side, such as Quick Sync and Turbo Boost 2.0, and we suggest that you read over our earlier article if you haven't done so already.