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How do I know what Processor is right for me?

Choosing the right CPU or Processor for your machine can be tricky, in this brief guide you should gain the knowledge you need to make an informed decission

What is a processor?

The processor is one of the most important components in a modern computer. The term processor, CPU, ‘brain’ and chip generally refer to the central processing unit. Every action and command your PC does depends on interaction with the CPU so its performance is crucial to the overall computer experience.

What do I need to look for in a processor?

There are thousands of different processors available so it is understandable to not be certain about how the different models compare in performance and which one is right for you.

Not that long ago comparing processors was very easy. A higher rated megahertz processor would make a faster PC, for example a 733MHz processor would make a faster PC than a 600MHz processor. As processor speeds have increased into the gigahertz (1000MHz is equivalent to 1GHz) range manufacturers have had to introduce confusing naming schemes. It is often harder to understand the naming scheme that Intel and AMD use than the technologies behind the processor!

Today comparing processors is no longer about finding the highest speed processor possible in MHz or GHz. To get the best performance you need to take into account the whole specification of the processor including the number of cores it has, system bus speed and the amount of cache to work out its performance.

It all sounds rather daunting but once you understand the principles you can easily compare models.

Here is a brief list of what the specifications mean:

Clock Speed: Usually listed in Mhz (Megahertz) or GHz (Gigahertz) this used to be the primary indicator of processor speed, although in recent years this has become less important. Both Intel and AMD have invested huge amounts of money in developing their processors to maximise the output of each and every clock cycle and in doing so they have made the actual clock speed less important. A 1000MHz processor today is approximately 17% faster than the previous generation when you compare Intel’s first generation i5 processors to their second generation.

Front Side Bus (FSB): The Front Side Bus is the connection point between the CPU and the motherboard chipset. Motherboard specifications will list the FSB, measured in MHz like the CPU clock speed. The combination of FSB speed and a processor's internal multiplier determines the final speed of the CPU itself. As with processors themselves, FSB speeds have grown astronomically in recent times, with modern motherboards supporting FSB speeds from 533MHz right up to 2000Mhz

Nanometres (nm): The easiest way of measuring the technological complexity of a CPU is to measure how many individual transistors can fit on the CPU itself. You will see many processors described as 45nm, 32nm or even 22nm. As the technology size in nm drops the size of the transistors decreases, this allows a 22nm processor to have many more transistors in the same physical package as a 45nm chip and increase performance massively. The lower the nanometre the processor is generally the more advanced the processor is.

L1/L2/L3 Cache: For the CPU to function it has to be fed with data to process, a bottleneck can easily arise if the data is far away, for example in the systems memory. This will take time to access as the data has to travel through many controllers and a physical distance to the CPU causing a delay. If the CPU doesn’t have to travel outside of itself to get the data it can number crunch more effectively. When the memory is built into the processor it is referred to as cache. As a general rule the more cache a CPU has per core the better its performance in programs.

Between these attributes you can compare processors although looking at reviews is the best way to judge the performance differences between different models.

What are 64-bit processors?

Almost all processors available to buy today are 64 bit capable. The reason processors and operating systems have moved from 32 bit to 64 bit is largely due to the limits in the amount of memory that a 32-bit CPU can access. A 32-bit CPU can only address 4GB (Gigabytes – 4096MB). For many uses this limit is fine however higher end computers often need 4GB or over to complete complicated tasks or get the best performance out of the very latest games.

A 64-bit processor does not face this problem as it allows the processor to access potentially 16 billion gigabytes of memory (16 Exabytes). Having a 64 bit data path also doubles the amount of data that can be fetched at any one time increasing the performance of a 64-bit processor when running 64-bit applications.

All of the current 64-bit processors are backwards compatible to 32-bit operating systems and programs, although if running a 32 bit operating system they will still suffer from the limit of 4GB of memory. Both CPU and Operating System need to be 64-bit to provide the enhanced compatibility and performance.

What is an APU?

An APU is the combination of a processor with a graphics chip. APU stands for Accelerated Processing Unit.  Combined onto the same silicon they improve data transfer rates between them and greatly improve performance over traditional integrated graphics solutions. As a general rule an APU at the same price as a normal processor will perform better in games and with multimedia playback than other integrated solutions. However even the best APU cannot match the performance of even a modest graphics card.

What is overclocking?

Many people probably don't know what overclocking is but have possibly heard the term used before. To put it in its simplest terms, overclocking is taking a computer component such as a processor and running at a specification higher than rated by the manufacturer. Every part produced by companies such as Intel and AMD are rated for specific speeds. They have tested the capabilities of the part and certified it for that given speed. Of course, most parts are underrated for increased reliability. Overclocking a part simply takes advantage of the unused potential already present within the specified parts

What are the benefits?

The primary benefit of overclocking is additional computer performance without the need to select a more expensive processor. Most individuals who overclock their system either want to try and produce the fastest desktop system possible or to extend their computer power on a limited budget. In some cases, with the right hardware and know-how it is possible to boost system performance by 50% or more!

How does overclocking work?

There are differences in overclocking each processor, processor series and there are differences between Intel & AMD yet the principles remain largely the same. To overclock settings are changed in the computers BIOS that result in the processor running at a higher speed.

There are three main settings that are changed to achieve an overclock in one of our systems or bundles:

FSB (Front Side Bus): The data bus that carries information from the processor to the main memory and the rest of the system. An internal multiplier determines the speed of the processor in MHz or GHz by multiplying the FSB speed of the system.

Multiplier: The ratio of a given processor's speed (in MHz or GHz) as compared to the FSB (Frontside Bus) speed of the PC it is installed in. A processor with an internal multiplier of 20x installed in a system with a FSB of 200MHz would run at 4.00GHz, since 20 x 200MHz = 4000MHz.

Memory Divider: Most modern motherboards allow a memory divider to be set. This divider allows the system memory to run slower than the actual FSB speed. By default, FSB speed and memory are usually set to a 1:1 ratio, meaning that increasing FSB speed (by overclocking) increases memory speed by the same amount often making the system unstable at higher speeds without the divider.

By increasing the FSB and selecting a lower memory divider it is often possible to greatly increase the performance of the components.

For example a PC with a processor running at 20 x 133MHz is running at a clock speed of 2.66GHz. When the setting is changed to 20 x 200MHz the processor speed will be increased by 1.33GHz. That results in a 50% overclock and a new processor speed of 4.00GHz! This will result in an increase of memory speed so a divider will have to be selected to ensure system stability.
For the components to run stable a complex set of voltages must be tweaked to provide the right power to run at the higher speeds. A performance cooler is always recommended to deal with the excess heat and always supplied when required on one of our systems or bundles.

Are there any risks?

As long as the components have been carefully selected, the settings expertly chosen and the cooling and power supply are able to cope with the excess stress there is only performance to gain from overclocking. With intensive stability testing it is possible to ensure system stability equal to that of a non-overclocked system.

The faster a computer goes, the more heat it produces. This is especially true when the voltage being fed to certain components is increased. Excess heat in the processor, motherboard chipset or memory can cause crashes and system instability so an upgraded processor cooler and well ventilated case is essential.

Overclocking a PC also increases the amount of power it draws, and this may lead to system instability if its old 300W power supply is not up to the task and may lead to spontaneous reboots. If you are running a modern high end overclocked system expect to need a quality branded 450W power supply or more. The brands to look for are Corsair, Coolermaster and Antec with all having excellent reputations and proven reliability. All of our overclocked full systems are provided with a high quality power supply for this reason.