CPU and Fans

Since at least the early sixties, computer scientists have referred to the circuitry that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output operations specified by the instructions as a Central Processing Unit, or CPU. We still call them that, even though what was once a roomful of electronic circuits has been shrunk and packaged into a single Integrated Circuit (or IC). And, if you're about to build a new computer, you'll need to figure out which one you want.

At the time of this writing, there are two primary companies making CPUs (that are compatible with the Windows operating systems): Intel and AMD. Both utilize the same machine instructions, making your choice of CPU transparent to any applications you choose to run on it. However, it does make a difference to your motherboard, which will support one or the other but not both.

So, generally, people will choose a motherboard based on features, or speed, or price—or all three—and then get an appropriate CPU to go with it.

Cores

Less than a decade ago, all processors came with a single core. These days, single-core processors are the exception and you are not likely to find a motherboard that would require one, or a CPU that has just one.

Multi-core processors have become more popular as their availability has become increasingly common and software has been designed to take advantage of multi-core technology. From dual-core to eight-core processors, there are a number of options to choose from. When deciding how many cores are needed, first it is necessary to understand what “multiple cores” means.

When processors were running on a single core, that one core was responsible for handling all the data sent to the processor. As more cores are integrated into a processor, those cores are able to split up the processor's tasks. This makes the processor faster and more efficient. However, it is important to remember that a processor can only perform as well as the existing software running it. If the software is only able to utilize three of the eight cores, then five cores are going to be unused. To maximize cost and use, it is best to match system requirements with core availability.

Modern versions of Windows can handle any number of cores dynamically; in general, it will assign each task to a different core, returning to the first only if it runs out of others. Wwith all else being equal, you are likely to experience a faster computer if you get a CPU with more cores than fewer.

Cache

A processor's cache is similar to the memory of a computer in that a processor's cache is a small amount of very fast memory that is used for temporary storage. This allows a computer to retrieve the files that are in the processor's cache very quickly. The larger a processor's cache, the more files it will be able to store for that quick retrieval.

The main reason that the cache is so fast is that it is, literally, built into the same IC as the cores.

So, given a choice of processors, the one with more and/or faster cache will, all else being equal, give you a faster computing experience.

Socket Compatibility

Socket compatibility refers to the interface between a motherboard and its CPU. If a motherboard has already been acquired, make sure that the processor installed is compatible with the motherboard's socket. Alternately, when building a computer around the processor, make sure that the motherboard is compatible with the existing processor.

Integrated Graphics Processing Units (GPUs)

Most of today's processors have integrated graphics processing units, which are designed to perform the calculations related to graphics. If a processor does not have an integrated GPU, the computer can still display graphics if a separate graphics card is present or if the motherboard offers onboard video. If the computer will be used for graphics-intensive software and programs, then a CPU with an integrated GPU will likely not perform as needed.

However, most motherboards have graphics processors built-in.

If your graphics needs are very demanding…you will use this computer for playing real-time video games, or to render CGI sequences for movies…you should have planned on getting a separate graphics card anyway, and the presence or absence of a GPU or built-in graphics won't make a difference (except leaving them out will lower the motherboard/CPU price).

Personally, for all the digital photography I do, I have found the graphics included on the motherboard to be quite adequate.

Frequency

The frequency of a CPU, measured in hertz (Hz), is the speed at which it operates. In the past, a merely faster frequency equaled better performance. This is not necessarily the case any longer. In some cases, a CPU running at a lower frequency may actually perform better than a processor running at a higher frequency due to the infrastructure of the CPU (for example, how many cores it has). It is important to look at a CPU's "instructions per clock" in addition to the frequency of the CPU. While frequency is still a good indication of how quickly a processor can perform, it is no longer the only factor that impacts the actual speed of a processor.

Fan

CPUs perform, literally, billions of instructions per second; and they use a lot of electricity to do it. That means CPUs get hot, sometimes very hot. And something must be done to escort that heat away from the CPU, because, if it gets too hot, it stops working.

Only a few years ago, CPUs and fans were sold separately, even though the fan was specific to the CPU. Nowadays, however, most CPUs come with the fan they will need. This fan will be fastened to the CPU, the better to suck the heat away from it and into the computer case.

Of course, the case can get too hot because of this. That's why the case typically comes with one or more built-in fans of its own. And the power supply has one of its own (to get rid of the heat it produces).

Don't forget that dust builds up inside the case, and dust is an excellent insulator that can even build up on moving fans. Please don't forget to open up your computer case periodically (at least once a year) and vacuum out the dust.