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What Does It Mean to Be CPU Bound?

Alex Newth
Alex Newth

The central processing unit (CPU) is an integral part of any computer, because it makes and controls most processes in a computer. While the CPU is in control of most of the processes, elements such as the memory or cache also contribute to helping processes finish. A CPU bound computer is one in which, instead of using the other components, the processes are bound exclusively to the CPU. A CPU bound system configuration has advantages and disadvantages. It has very quick processing if the CPU is powerful, but it also creates an imbalance because the other components are going unused.

When a system is CPU bound, it means that only the CPU is working on all the processes. During this time, the CPU may be using from 90 percent to 100 percent of its energy, rather than the 10 percent to 20 percent it uses at other times. If the CPU is fast, then this will speed up processing and make the computer faster overall. This normally happens with programs that require calculations, such as calculators and spreadsheet programs. Programs with graphics and any other type of processing will not do well with a CPU system.

A dual core CPU mounted to a motherboard.
A dual core CPU mounted to a motherboard.

Unlike in other systems, in which the computer relies on other components to help processing, only the CPU is being used if it is CPU bound. When someone wants to speed up a computer, he or she normally adds more random access memory (RAM) or other components. For CPU bound computers, only the CPU should be upgraded, because these other memory components do not matter.

A Central Processing Unit (CPU).
A Central Processing Unit (CPU).

There are three other types of bound systems: input/output (I/O) bound, memory bound and cache bound. I/O bound means the system is bound to the I/O information; it is best used in a program in which lines have to be counted. A memory bound system is best at processing large amounts of data, and is bound by memory components such as RAM. A cache bound system, which is a subset of memory, works the same as a memory bound system, only it processes data that have already been encountered.

The advantages of having a CPU bound system are as numerous as the disadvantages. Of all the bound systems, the CPU is the fastest and tends to be the most used. If programs with calculations are primarily used, then the CPU system will be working at its best. Instead of having to upgrade other components, the user will only have to focus on upgrading the CPU to improve performance.

On the side of disadvantages, having a CPU system can make the computer imbalanced, because it is not taking advantage of the other processing components. CPUs tend to be expensive, so upgrades can become costly. While the CPU is fast, it will only be able to work on a few processes at a time. This means that, if the user has several programs open, only one or two will be working quickly, while the others will hardly move.

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Discussion Comments


Have any CPU bound computers ever caught on with the public? While there are some advantages in terms of calculations, it seems those advantages were nullified in the 1980s with the advent of the match coprocessor that did such "heavy lifting" while the CPU was taking care of other things.

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    • A dual core CPU mounted to a motherboard.
      A dual core CPU mounted to a motherboard.
    • A Central Processing Unit (CPU).
      By: Gudellaphoto
      A Central Processing Unit (CPU).