5 Key Computer Hardware Components

If you want to understand computers, you have to understand computer hardware components. A machine is the sum of its parts, and five parts in particular make computers what they are today.

Component #1—A Surprise

I was going to start this article by talking about the computer processing unit—after all, what’s a computer without a computer processor? But then I thought to myself, what’s a computer without electricity?

The power supply, often abbreviated PS, is an often neglected but entirely essential part of every working computer. If the computer processing unit is the mind of a computer, the power supply is its heart—hard working and undervalued until it stops working.

Obviously power supplies provide power to the individual parts of a computer, but that’s oversimplifying their job. The different parts of your computer expect different voltages and wattages. It’s up to your power supply to convert the electricity coming from your wall into all of these different combinations which your computer requires.

Making this job even more difficult is the general rottenness of home power delivery. In many places, power comes in relatively unevenly—you’ve probably noticed your lights flickering during a thunderstorm, but tiny shorter power fluctuations like that are happening all of the time even on the nicest day.

Electronics, especially the sensitive ones in a computer, don’t like those fluctuations. A tiny, barely-measurable fluctuation at the wrong time can cause your computer processor to drop a decimal point which, in turn, can crash your computer. (Computers hate bad math.)

So a quality power supply includes not just an inverter to alter the voltage type but capacitors and regulators to filter out drops and peaks in power. Yet for all of its hard work, your power supply hardly gets any recognition at all.

Component #2—The Mind Without Memory

The number one computer hardware component people want to know about is the computer processing unit (CPU). How fast is it? How many cores does it have? Is it 32 or 64 bits?

For all of the attention paid to it, most of the time your CPU does absolutely nothing. It’s like an efficient secretary who does all of the paperwork the moment it hits her desk—and then spends the rest of the day painting her nails.

However, it feels like your computer is always working, and that’s because your computer can think much, much faster than you can. On a typical modern computer, when you move your mouse just slightly, your computer takes a few microseconds—that’s a a few millionths of a second—to redrew the mouse cursor on your desktop. It takes your monitor up to 5 milliseconds just to draw that image (5 milliseconds is 5,000 microseconds) and then it takes the typical person 10–20 more milliseconds to notice the change. So your computer processing unit does about 5 microseconds of work and you don’t finish noticing it until about 25,000 microseconds later. No wonder science fiction writers worry so much about computers taking over the world.

Lucky for us humans, fast computers are still dumb computers. Your computer processing unit can only do a few basic operations and each operation can only use a few variables (which are stored in a special part of the CPU called a register). If the computer wasn’t designed to perform a particular operation, it either can’t do it or it needs a program on your computer to convert the problem into a set of operations the computer processor can perform—for example, a program on your computer converts every letter you see into numbers so the computer can work on them.

Component #3—64 Millisecond Amnesiac

Some people have really bad memories, but imagine someone who forgets everything in 64 milliseconds unless you remind him. That’s exactly how your computer memory works. (The main computer memory on your computer is called Random Access Memory [RAM]).

The memory chips on your computer are specially designed to hold an electrical charge for a very short amount of time, typically 64 milliseconds. After that time expires, the charge quickly fades away unless your computer refreshes it.

It seems to me that refreshing possibly gigabytes worth of memory every 64 milliseconds would consume too much time, but in modern RAM, the refresh cycle only slows your computer down by about one percent.

The only problem computer scientists have found with typical computer memory is that refreshing the memory every 64 milliseconds (15 times per second) uses up extra power. These days as computer manufactures make smaller and slimmer devices, there’s a push to reduce power consumption, so researchers are working on advanced persistent computer memory which doesn’t need to be refreshed periodically or which just doesn’t need to be refreshed as often. IBM estimates that replacing typical computer memory with persistent computer memory can triple the battery life of a typical laptop.

Component #4—More RPM Than A Race Car

One of the marvels of modern engineering sits inside most of our computers—the hard drive. Here is a tiny little box which stores gigabytes or even terabytes of data that we can retrieve in milliseconds.

To manage this incredible feat, the hard drive is built to amazing tolerances. Dozens or hundreds of tiny disks thinner than a sheet of paper rotate over some of the most precise ball bearings ever made. The disks rotate 5,000 to 20,000 times per minute (RPM), meaning the ball bearings rotate dozens of times faster than that.

The earliest hard drives were as big as refrigerators and stored only a few megabytes. Today hard drives and their successors, solid state drives, continue to push the barrier of what’s even possible.

Component #5—How Computers Conquered The World

The last component on our list today has undergone more changes than all the others combined. It’s the expansion port. On the original PCs—before Macs existed—many accessories had to be hardwired into a computer. (And heaven help him that soldered the positive and negative connections backwards!)

Later came specific slots in a computer that could accept a wide variety of accessories. The most popular early standard was ISA cards, and you could still find new computers with vestigial ISA ports just a few years ago. Then came the second most popular standard of all time—PCI ports. These reigned supreme throughout the 1990s. If you wanted at add an accessory to your computer, you got it on a PCI card.

PCI was slowly supplanted in the late 1990s and early 2000s by a standard we’re all familiar with—USB. USB did us a great service by moving the accessories outside a computer where there’s more space and more flexibility. USB also lets us add or remove devices without turning off the computer, which is an incredible convenience.

USB has been through several standards and it’s seen some competing protocols for specific kinds of devices (mostly disk drives and computer monitor cables), but the newest USB 3.0 protocol seems like it will take its place alongside early USB protocols in the history of popular computer hardware components.


  1. Christopher says

    Power supply is definitely key, and next on my list would be get as much RAM as your motherboard will hold! People don’t realize how important RAM is in running their computers. They look at the processor speed and the space of the hard drive but without a good amount of RAM, certain programs won’t run optimally.

    • says

      Yes you are right, RAM can really speed up your computer. I used to build and fix computers and adding one extra piece of RAM was amazing for a computer. I also like to have as much as my slots will allow. :)

  2. says

    Hi David,

    A very good and useful article. In my opininion, the Random Access Memory is very important. Most people buy a computer with a fast processor incorporated. But if the Random Access Memory isn’t fast enough, then the processor won’t help you as much.

    Once again, a very good and useful article,