A brief guide to PC processors (CPUs)

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intel-logoAt the heart of any computer is the central processing unit (CPU) or processor.  The processor is though by most DIY system builders to the most important component in any build, however, as important as it is, a computer will only be as fast as it's slowest component.  Therefore thought should also be put into building a balanced system and investing as much money in the motherboard, memory, graphics card (GPU), power supply (PSU), case and hard drives so as to obtain the best trade-off between speed and reliability.

For the DIY computer builder, there are really only two realistic options, either a chip manufactured by AMD, or one built by Intel.  Both manufacturers' CPUs are reliable, but there is always an ongoing battle between the two manufacturers to provide the best CPU.  There has never been a clear winner between the two manufacturers over the years and the choice of which processor to purchase simply comes down to the fastest chip in your price range (which can be determined by processor benchmarking).  There are many sites that provide CPU benchmarks and the majority of CPUs have been tested by enthusiasts.  In general, however, unless you are looking to build a really expensive PC, processors of a similar price tend to provide very similar speeds with faster processors costing more and the latest releases giving rise to an exponential rise in cost.

amd cpu processorsThe important thing to note on the choice of CPU is that it determines the motherboard that can be used in the system due to the socket required for installation of the CPU.

The current AMD socket types for support of AMD processors are the AM2, AM2+, and AM3 sockets.  The AM type sockets were designed to supersede the original Socket 939 and 754 types.  AM2 sockets support the AMD Athlon 64 and AMD Athlon 64 X2 processors and provide support for DDR2 memory.   The AM2+ socket is basically an intermediate between the AM2 and the AM3 socket providing support for AMD Athlon 64, AMD Athlon X2, and AMD Phenom CPUs, whilst still providing support for both the existing AM2 and new AM3 socket processors.  The AM3 socket is the latest release of the socket type supporting the Phenom II range of processors and DDR3 memory.  It is important to note that AM2 and AM2+ CPUs will NOT work in the AM3 socket motherboards. The AM sockets all follow the same form and the CPU itself has pins that align with holes in the socket, with orientation shown by an arrow on the processor that aligns with a similar one on the socket (See the photos below for examples of the socket and a processor).


The Intel socket types are the LGA775 (Socket T) which has now been superseded by the LGA 1388 (Socket B). The LGA775 socket type supports the Intel Pentium 4, Intel Pentium D, Intel Celeron, Intel Celeron D, Intel Pentium XE, Intel Core 2 processors (Including the Solo, Duo, Quad and Extreme).   The LGA 1156 and 1388 sockets are the latest socket revisions from Intel designed to support the new Intel Core  processors (i3, i5 and i7).

Socket types are different in comparison to the AMD sockets in that the "pins" are located in the socket on the motherboard, and the processor has contact points that align with these pins, however, orientation of the processor in the socket is again denoted by a small printed arrow on the corner of the XPU which aligns with an arrow on the socket (See the photos below for examples of the socket and a processor)It is important to note that there is NO cross compatibility between the two socket types.


When deciding between the manufacturers and indeed CPU or processor model it is important to make sure that the motherboard decided on will support the processor and vice versa.  Additionally before finally deciding it is often worth checking how the processor perform in relation to their price so as to make sure to get the best performance for money (An excellent resource for comparing common CPUs is available here). In general however, the more expensive the chip is, the faster the perfomance you will see and therefore the better your experience will be when using your PC.

Of course, another option to further improve the speed of a system is overclocking to boost the performance of the CPU but that will be covered in another article, as will choosing between the various methods of cooling available for CPUs.