Hardware > Troubleshooting Hardware Problems

“What's in There?”: Opening Up the Box

By Michelle Murrain

For most people, a PC is a box that never gets opened, and is somewhat mysterious, except perhaps for the things we plug into it. This article is an overview of the major hardware components of a PC, what those components do, and what can be done if something goes wrong.

Areas covered in this articile:

• Basic components of a PC and what they do: CPU, motherboard, hard drives, memory and other components.
• How to troubleshoot hardware problems
• How to build your own PC

Opening a PC (or, heaven forfend, a laptop) can be daunting. There are all of those differently-coloured cables and wires, and all those strange looking fans and things. There's so much in there, it seems. If you're interested in some experimentation, and want try out opening up the box, and delving in, here is a short guide for you.

It's all actually pretty understandable. A computer basically consists of three major aspects: the brain (that's the CPU, more about that later), things that help the brain think and remember, and things that help you interact with the brain. In some ways, although a computer doesn't walk, it can “hear” (that is, take in input) and “speak” (that is, put out data.) And everything inside the box helps in that process.

So let's describe what's in a computer on the physical level.

The case

The case is just what holds it all together. Cases are designed these days to be fairly easy to open, and there is a place for all of the components to go.  The case has places for all of the varied drives, fans, the motherboard, and power supply. Often, if you buy a case, the power supply will come with the case.

In a laptop, all of the same elements are there, they are just much smaller and crammed into a smaller space.

Photo by jules:g

Hard Drives

Hard drives hold most of the data that the computer needs. They hold the operating system, and all of your user data, like documents, photos, and music. Hard drives are generally found in sizes from 50 GB to 1 TB. Very old computers may have hard drive sizes as small as 100 MB. Hard drive capacity is increasing quickly – 500 GB drives are common, and not very expensive. 1 TB drives are beginning to also become reasonably priced.

Hard drives for most desktop computers are 3.5” wide. Laptop hard drives are 2.5” wide.

There are two hard drive standards right now, IDE/PATA (Integrated Drive Electronics, which has now been renamed to PATA, for Parallel Advanced Technology Attachment), which is fading, and SATA (Serial Advanced Technology Attachment), which is becoming the new standard. PATA drives require wide (and length-limited) cables, and are much slower than SATA drives. Both hard drives and CD/DVD drives can use PATA or SATA. All modern motherboards have connectors for both.

Other drives

There are several kinds of other media drives that you might find in a computer these days. One essential is an optical drive. Most drives are now at least CD readers, as well as CD writers (CD-R/RW). Many are DVD readers, and CD readers/writers. Some are also DVD writers, and will write a variety of DVD formats. The bleeding-edge optical drives are Blu-ray or HD-DVD, which use a different color laser, which allows them to store data on those discs at a much higher capacity. Blu-ray or HD-DVD drives for PCs are still very expensive (above £400.)

Most desktop computers, until about a couple of years ago, also had a floppy disk drive. These have basically become obsolete, and most new computers shipped do not have floppies. Most motherboards that you can buy still carry support for floppy drives, however.

The motherboard

The motherboard is the most important part of the computer. If anything ever goes wrong with it, it has to be replaced, and it makes the computer as a whole pretty much unusable. The motherboard holds the CPU, chipsets (called “Northbridge” and, often “Southbridge” which help the CPU work, and interface with other components), slots for memory and expansion cards, as well as places for a varied number of connectors from drives, the case, and the power supply.

photo by viagallery.com

Central Processing Unit (CPU)

The CPU is where all of the processing occurs. The CPU executes “programs” - and it is these programs that make up what a computer does. Everything a computer does is passed through the CPU, in the form of binary programs that it executes.

Memory

Memory is important, because it holds the state of the computer at any moment. When you are using a computer, the operating system environment, and applications you are running are located all in memory, which is why when you turn off a computer, you've lost things you are working on, and you have to start up applications from scratch. (When an application starts automatically on start-up, it is because there is a setting somewhere on the hard drive which indicates which programs should be running on start-up.

Right now, memory is most often in the form of DIMMs (Dual In-line Memory Modules). Most DIMMS are from 256 MB to 2 GB. Most modern motherboards have the capacity for 4 DIMMS, and usually have a capacity for 1-8 GB.

Expansion Cards

It used to be that a motherboard had only the very barest of input and outputs – serial, parallel (for printers) and keyboard and mouse. Everything else needed to be put on an expansion card. Modern motherboards have onboard sound, onboard video, onboard modem and networking, USB, Firewire (or IEEE 1394) – basically everything you need, all in one place. Primarily, expansion cards now are for video cards (especially high end cards), wireless cards (few, if any, desktop motherboards or computers come with wireless adapters,) and other specialty cards. PCI (Peripheral Component Interconnect) is a specific kind of slot for an expansion card. Most motherboards still have PCI slots. The newer standard is called PCIe (PCI express) which is much faster.  Some motherboards, however, do not have onboard video – so you'll see a video card. Often, these cards use what is called the AGP (Advanced Graphics Port) slot.

Fans and heatsinks

These days, keeping the CPU and memory cool are imperatives. CPUs run hotter than they ever had, because they are packing more and more transistors into a smaller and smaller space, leading to more heat creation.

photo by pauledely

Cables

There are a lot of cables inside a computer case. The most prominent ones are the cables going from the power supply to everything inside the case: the motherboard, fans, hard drives, and CD/DVD drive(s). Second most prominent are the cables from the motherboard to the hard drives and CD/DVD drives.

How do you troubleshoot a hardware problem?

First, it's important to know whether or not it is a hardware problem, or a software problem. In general, hardware problems are quite dramatic – the system won't boot up at all, a hard drive disappears from view, the display acts quite strange, or flickers and fades. Sometimes, hardware problems can appear more subtle (like an intermittent problem in a CD/DVD drive might not seem so major.

The easiest way to troubleshoot hardware problems is to swap out components. For instance, if your video starts to look strange, and doesn't seem to be working right, swapping a new video card for the old is a way to find out if that was the problem. Memory problems are often caught by the motherboard's BIOS, and you can do memory tests. You can also swap in another direction – have a hard drive that you are suspicious of? Put it into a different computer that you know is working. What happens?

Basically, your goal in troubleshooting is to isolate the component that is causing the problem. Then you can replace it. (Repairing these is basically impossible.) And the good thing is that most of these components can be inexpensive, so if you are doing these replacements yourself, you won't spend a lot of money.

However, replacing a motherboard on a brand-name PC (like Dell, or HP) will not be inexpensive.

Building your own PC

Building your own desktop PC is a lot less difficult than you'd expect. In fact, the actual building of the PC is quite easy, and can take less than a couple of hours. Even less once you've done it a few times. Most of the work you'll spend figuring out what kind of CPU, motherboard, video and memory you want. The rest is quite straightforward. There are some good books on the topic, and they are worth getting. One is called “Building the Perfect PC.”

First decide whether you want an Intel processor or an AMD processor. Intel is the standard, and their high-end processors are fastest (and most expensive). AMD, the competitor, has processors that generally aren't as fast, but are more energy efficient, and more inexpensive.

It is mostly a matter of preference, but definitely read reviews of processors – there have been some duds you don't want to buy. Tom's hardware, and Anandtech are both great sites for detailed info on CPUs.

Conclusion

Looking inside a PC box, and understanding what's inside is easier than you think. And learning how to replace parts, and understand how to put a PC together can save you money. And it can be fun, too!