Intel Core i7 Mobile CPU (Clarksfield) Review

Introduction and Specifications

For quite some time now, Intel has been the undisputed leader when it comes to laptop CPU performance. This advantage comes from the fact that Intel has successfully scaled its desktop processor technology for use in the mobile platform. That trend continues with the latest mobile processor platform being unleashed today from Intel: the "Clarksfield"-based Core i7 Mobile processor family and the new PM55 Express Chipset.

This marks the first time that the "Nehalem" Core i7 microarchitecture has been ported over to the mobile side. The fact that the mobile version of Nehalem makes its debut only two weeks following the
launch of Intel's Core i5 ("Lynnfield") mainstream desktop CPU and P55 Express chipset is no coincidence. As it turns out, the Core i7 Mobile processor die is identical to the desktop version, but uses mobile packaging--as far as the microarchitecture is concerned, Clarksfield and Lynnfield are essentially the same thing. The lower power demands of Lynnfield (as opposed to the original Nehalem architecture) are in large part what enable it to also be used in notebooks.

What this means is that Core i7 Mobile-based notebooks will see a number of the same benefits that Core i7 desktops already have, such as integrating the memory controller into the processor die, using a three-level cache hierarchy, utilizing Hyper-Threading technology, and taking advantage of Intel Turbo Boost Technology. What Lynnfield/Clarksfield adds to the equation is on-die PCI Express connectivity, getting rid of the Northbridge chip, and improving the Intel Turbo Boost Technology (from the original Nehalem architecture). Additionally, whereas only the previous Intel Core 2 mobile ("Penryn") microarchitecture had primarily dual-core offerings, all of the Core i7 Mobile solutions are quad cores. The three Penryn-based quad-core mobile processors (the 2.53GHz Core 2 Extreme QX9300, 2.26GHz Core 2 Quad Mobile Q9100, and 2.0GHz Core 2 Quad Mobile Q9000) are made from two dual-core chips merged together in a single CPU package, while Clarksfield uses a single-chip (monolithic) design.

Intel Core i7 Mobile Processors
Specifications & Features

  • Core Frequencies:
    2.0GHz (i7-920XM), 1.73GHz (i7-820QM), 1.6GHz (i7-720QM)
  • Maximum Turbo Boost Frequencies (single core):
    3.2GHz (i7-920XM), 3.06GHz (i7-820QM), 2.8GHz (i7-720QM)
  • Number of CPU Cores - 4 (8 Threads w/ Hyper-threading)
  • L1 Cache: 256K (32K x 4 Instruction, 32K x 4 Data)
  • L2 Cache - 1MB (256K x 4)
  • L3 Cache - 8MB shared (i7-920XM and i7-820QM); 6MB shared (i7-720QM)
  • Shared Smart Cache Technology
  • Maximum TDP (Thermal Design Power) – 55W (i7-920XM), 45W (i7-820QM and i7-720QM)
  • .045-micron (45nm) manufacturing process
  • Stepping - 5
  • DMI Speed - 2GB/s
  • PECI Enabled
  • Enhanced Intel SpeedStep Technology (EIST)
  • Extended HALT State (C1E) Enabled
  • Execute Disable Bit (XD) Enabled
  • Intel Turbo Boost Technology
  • Intel 64 Technology
  • Intel Virtualization Technology (VT)
  • Intel Trusted Execution Technology


  • Intel Streaming SIMD Extensions 4.1 (Intel SSE4.1)
  • Supplemental Streaming SIMD Extensions 4.2 (Intel SSE4.2)
  • Intel Hyper-Threading Technology
  • Packaging - 37.5mm square rPGA Socket (rPGA988A)
  • Total Die Size - Approximately 296mm2
  • Approximately 774M Transistors
  • PCI Express - One, 16-lane PCI Express port configurable to two, 8-lane PCI Express ports intended for graphics attach; 2.5 GT/s and 5.0 GT/s PCI Express frequencies are supported.
  • Memory Support:
    - One or two channels of DDR3 memory with a maximum of one SO-DIMM per channel
    - Single- and dual-channel memory organization modes
    - Memory DDR3 data transfer rates of 1066 MT/s and 1333 MT/s
    - DDR3 I/O Voltage of 1.5 V
    - Non-ECC, unbuffered DDR3 SO-DIMMs only
  • Pricing (1K units) - $1,054 (i7-920XM), $564 (i7-820QM), $364 (i7-720QM)

45nm Lynnfield/Clarksfield Quad-Core Wafer

Core i7 Mobile processors are available in three versions. The flagship processor is the Core i7-920XM, which has a base speed of 2.0GHz and goes up to 3.2GHz using Turbo Boost. The middle CPU is the Core i7-820QM, which has a base speed of 1.73GHz and can go up to 3.06GHz with Turbo Boost. Last, but not least, is the Core i7-720QM, with a base speed of 1.6GHz and maximum Turbo Boost speed of 2.8GHz. The Core i7-920XM and Core i7-820QM both have 8MB of shared L3 Smart Cache, while the Core i7-720QM has 6MB of L3 Smart Cache. The other notable difference between these three processors is that the Core i7-920XM has a maximum TDP of 55W, while the Core i7-820QM and Core 720QM both have a maximum 45W TDP. (For comparison, the three quad-core Penryn processors all have a maximum TDP of 45W).

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