Intel Core i7 Mobile CPU (Clarksfield) Review

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The Core i7 has a die size of approximately 296mm2 and contains roughly 774-million transistors. The die includes four physical execution cores, three levels of cache, an integrated memory controller, and PCI Express interconnects.


Lynnfield/Clarksfield Die Map

Since the Core i7 Mobile processor integrates the memory controller and PCI Express interconnects onto the processor, there is no need for a traditional Northbridge chip. This means that the PM55 chipset acts primarily as a Southbridge chip, handling most of the device I/O. With no Northbridge chip to communicate with, the Core i7 Mobile processor doesn't need the Intel QuickPath Interconnect (QPI) that the Core i7-900 series ("Bloomfield") processors use to communicate with the chipset. Instead, the Core i7 Mobile uses the slower Direct Media Interface (DMI) interconnect to communicate with the PM55 chipset. Another major difference between the Core i7 Mobile and the Core i7 900-series, is that unlike the Core i7 900-series support for triple-channel DDR3 memory, the Core i7 Mobile instead supports just dual-channel DDR3. The Core i7 Mobile processor supports configurations of 16 PCI Express 2.0 lanes per GPU or two sets of 8 PCI Express 2.0 lanes.


With the memory controller and PCI Express interconnects on the processor die,
the Core i7 Mobile doesn't need a Northbridge chip.

The Core i7-920XM and Core i7-820QM processors have the same three-level cache architecture as all other existing Core i7 and Core i5 processors. The cache configuration is made up of a 4 x 32K instruction L1 cache, 4 x 32K data L1 cache, 4 x 256K L2 cache, and an 8MB L3 cache that is shared between all four cores. The Core i7-720QM has the same L1 and L2 cache amounts, but instead has 6MB L3 shared cache.


All Core i7 Mobile CPUs have three levels of cache; the
Core i7-920XM and Core i7-820QM have 8MB of shared
L3 cache (the Core i7-720QM has 6B of shared L3 cache).


Also, as with all other Core i7 processors, the Core i7 Mobile includes Hyper-Threading support. Hyper-Threading allows each core to process two simultaneous threads. As a result, the Core i7 Mobile can run up to eight simultaneous threads.


With Hyper-Threading, the Core i7-920MX has four physical execution cores and
four virtual cores, for a total of eight cores available for multi-threaded workloads.


As you can see in the Windows 7 Resource Monitor screenshot above, the system sees a total of eight cores: four physical execution cores plus four virtual cores via Hyper-Threading.

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