Intel Core i7-840QM Mobile processor (BY80607002901AI / BX80607I7840QM)

Core i7-840QM is an evolutionary update to i7-8xx line up of high-performance Core i7 Mobile microprocessors. The processor was released on June 20, 2010, along with two other Core i7 mobile CPUs - i7-940XM and i7-740QM. Even before the official launch, the Core i7-840QM processors were spotted in a number of announced notebooks - Dell Studio 14 and Studio 15, EUROCOM X8100 Leopard, Fujitsu Celsius H700 laptop, Lenovo Y560d notebook, and Mouse Computer Company MB-G811B and MB-G811S laptop models.

The Core i7-840QM processor is based on Clarksfield core, which integrates the following components on a single die:

• 4 microprocessors cores. Each core has its own 64KB level 1 and 256 KB level 2 caches.
• 8 MB level 3 cache, shared between all cores. The cache is inclusive, that is it also includes data cached by L1 and L2 caches of all cores.
• Integrated memory controller is used to access DDR3 memory. The controller supports single- and dual-channel memory modes. Memory bandwidth is doubled in dual-channel mode, which marginally increases CPU performance.
• Direct Media Interface is used to communicate with peripheral devices.

The Intel Core i7-840QM CPU runs at 1.86 GHz, and comes with numerious advanced features: 64-bit instruction set, SIMD instructions up from SSE to SSE4, Virtualization technology, and Vpro features (VT-d and Trusted Execution Technology). The Core i7-840QM also supports Hyper-Threading (HT) technology. This technology adds second set of general and special registers to each CPU core, which allows each core to process two threads at once, which, in turn, leads to better utilization of core resources and improved core performance. Another useful feature is Turbo Boost technology. When the processor is operating within thermal limits, this feature temporary enhances performance by bumping processor's frequency. The frequency boost depends on the number of active cores, and for the Core i7-840QM CPU the boost can be as high as 266 MHz for 4 and 3 cores, 1067 MHz for 2 cores, and 1333 MHz for 1 core.

The core i7-840QM processor includes a few power-saving modes, that may operate on per-thread, per-core or per-package level. These modes are used to suspend one or more CPU cores for very short (microseconds) or indefinitely long periods of times. While they provide excellent power-savings capabilities, they are not useful when the cores are continiously processing data. In this case battery life can be pro-longed with the help of Enhanced SpeedStep technology, which reduces processor voltage and frequency, thus lowering CPU power consumption while the processor is still been able to run programs.

Like other Core i7 Mobile microprocessors, the i7-840QM is fabricated in 988-pin micro-PGA package, compatible wih socket 988 motherboards.

Compared with the Core i7-940XM CPU, the i7-840QM has a few advantages and disadvantages. The disadvantages are 840QM's locked clock multiplier, and lower CPU frequency. The advantages of this microprocessor are better power consumption, and slightly superior performance in Turbo Boost mode for single-threaded applications. Currently the CPU is priced at $568 - almost twice cheaper than the Core i7-940XM.