Designing the Perfect PC

Central Processing Unit (CPU)
The CPU is often considered the most important component within a PC. Whether this is true or not is up for debate, but rest assured, the PC will not function without one. Technologies such as NVIDIA’s CUDA platform may one day make CPUs less important due to the inherent architectural advantages of modern GPUs, but that day is while off just yet. A growing area of interest resides with GPGPUs, General-Purpose Graphics Processing Units, however. These allow otherwise dedicated GPUs to be used for general purpose tasks which the CPU is normally assigned to; in doing so the parallel processing nature of GPUs struts its architectural speed advantage.

Despite this technological advantage, GPGPUs are still a distant future in terms of practicality mainly because of the lack of data prediction and the specialised instruction sets they require; therefore a CPU is still well and truly important. Choosing a CPU isn’t particularly complicated if you follow a few simple guidelines. Firstly the main components of the Central Processing Unit must be established.

Cache: Cache is high-speed memory in which the CPU stores data to be processed. The larger the capacity of any given level of cache, the greater the performance. Data which does not fit within the integrated CPU cache is sent off-die to be stored in RAM. On die cache is split into layers, often two or three, each decreasing in speed and increasing in capacity respectively. Therefore, L1 cache is the fastest yet smallest capacity, L2 is larger and slower, and L3 (if the CPU contains such a level) is slower still with the largest capacity.

Cores: The amount of cores defines how many threads that can be efficiently processed at one time. This improves performance, although many applications are still limited to utilising one or two cores at a time. The operating system used also influences the performance of multiple core systems; Vista is better than XP in this regard.

Clock speed: Clock speed is often misused when comparing CPUs. The clock speed is the amount of clock cycles per second measured in Hz (or GHz). Clock speed is not an appropriate method of judging processing performance because it doesn’t define the amount of data being processed within each clock cycle.

Multiplier: The multiplier is a numerical value which defines the clock speed of the CPU. Higher multipliers are sought after by overclockers, but are usually accompanied by a hefty price tag. Finding the right balance between price and multiplier is a major factor when choosing budget overclocking gear.

Choosing a CPU
CPU selection encompasses the following performance groups:

Performance/Enthusiast/Overclocker: This clique strives to find the highest multiplier they can within their budget. This is also dependant on other key features such as cache and cores, although higher values may decrease overclocking potential. Also, smaller manufacturing processes are desired due to the reduced heat and reduced power consumption.

A great example of budget CPU overclocking performance includes the E8500/E8600 and Q6600/Q6700 Intel CPUs. With 9.5x/10x and 9x/10x multipliers respectively, their overclocking potential is nothing short of mind blowing.
Server: Servers often use specific CPUs designed for accurate computation and high stability, such as Intel’s Xeon and AMD’s Opteron range. These CPUs typically contain larger cache capacity and are of a higher grade binning.

Binning is the process of sorting components into performance ‘bins’. CPUs are tested until they are no longer stable, and when this limit is reached, they are placed into a particular ‘bin’ depending on the performance demonstrated. It’s not uncommon for server CPUs to use different sockets than desktop CPUs, so keep this in mind when choosing a motherboard/CPU combo.

What to research
Using a search engine such as Google is helpful when locating information in relation to the details above. Find model names of CPUs within your price range, and compare benchmarks on tech sites. The best way to find suitable parts is to browse reputable computer forums (such as Atomic) for advice.
Never select a CPU (or any component for that matter) based solely on brand name; always seek benchmarks which show how particular models perform from each brand.