Table 1-1 Common Multicore CPUs

Manufacturer	CPU Model	Number of Cores
Intel	Core i7	4, 6 (desktop); 2, 4 (mobile)
	Core i5	2, 4 (desktop); 2 (mobile)
	Core i3	2 (desktop, mobile)
	Core2 Quad
	Core2 Duo
	Pentium D
AMD	FX 8xxx, 6xxx, 4xxx	8xxx (8), 6xxx (6), 4xxx (4)
	Phenom II X6, X4, X3	X6 (6), X4 (4), X3 (3)
	Athlon II X4, X3, X2	X4 (4), X3 (3), X2 (2)
	Athlon 64 X2
	A8, A6, A4	A8 (4), A6 (4), A2 (2)

 

 

Large amounts of shared cache memory also help multicore processors provide better perfor-mance. Cache is a temporary storage for the core so that it can “remember” the most recent pro-cesses. It is like looking up a topic in this Quick Reference guide as opposed to a giant 900-page A+ exam-preparation book.

 

There are three levels of cache:

 

Level one cache (L1 cache) is located in the CPU core.

 

Originally, level two cache (L2 cache) was located on the motherboard in either removable or soldered memory chips or modules. However, almost all processors for a number of years now include L2 cache as part of the CPU die.

 

Level three cache (L3 cache), when present, is cache memory also located on the CPU die.

 

Level one, level two, and level three refer to the order in which the processor checks for informa-tion it needs to retrieve from memory. If the processor finds the information needed in level one, it uses it. If not, it checks level two, and so on. The processor checks main memory only if none of the cache memory contains the needed information.

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Hyperthreading

 

Hyperthreading (also known as HT Technology) is a feature found in many single-core and some multicore processors made by Intel. It enables a processor core to run two execution threads at the same time. If you use multithreaded applications (applications that have more than one process happening at the same time), enabling HT Technology in the system BIOS can improve perfor-mance. To determine if a particular Intel processor supports HT Technology, look it up at the Intel ARK website (http://ark.intel.com).

 

Virtualization Support

 

Virtualization is the process of running one or more operating systems inside separate windows on the same computer. For example, you could run Windows XP inside a window on a computer while it runs Windows 7. Almost all current AMD and many current Intel processors support hard-ware-assisted virtualization, which improves the performance of virtualized operating systems.

 

Intel uses the term VT-x to identify processors that support virtualization, while AMD uses the term AMD-V. To enable hardware-assisted virtualization support, you must have a processor that supports this feature and enable this feature in the system BIOS.

 

Integrated Graphics (GPU)

 

Although computers have featured graphics (video) components on the motherboard for many years, only recently have CPUs actually incorporated graphics components in the CPU die itself.

 

Intel’s Core i3, Core i5, and some Core i7 desktop processors (and all mobile processor in these families) include integrated graphics, although not all motherboards used with these processors support the feature.

 

AMD uses the term Accelerated Processing Unit (APU) to refer to its processors with integrated graphics. These processors are collectively referred to AMD Fusion.