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What you need to know before building your own computer

The second part of CNET's guide to building your own computer teaches you about the components you need to get the job done.

Dan Graziano Associate Editor / How To
Dan Graziano is an associate editor for CNET. His work has appeared on BGR, Fox News, Fox Business, and Yahoo News, among other publications. When he isn't tinkering with the latest gadgets and gizmos, he can be found enjoying the sights and sounds of New York City.
Dan Graziano
10 min read

This is the second part of CNET's guide to building your own computer. Make sure you read part one before proceeding.

Now that you have decided to build your own computer, you must have a basic understanding of what each component does. You didn't really think we would just jump right into building it, did you? These are the components that are found inside today's desktop computers:

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The operating system and all your files are stored on your computer's internal storage. There are two different kinds of storage options available: hard disk or solid-state. The cheaper option is to go with a traditional hard disk, as these drives are available at a lower price per gigabyte.

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Hard disks contain small moving parts that are more fragile than their solid-state counterparts, and while they can be had for significantly less, there are some drawbacks. Your computer will not power on as fast as it would with a solid-state drive, and it will also experience slower read and write speeds.

Solid-state drives, on the other hand, are relatively new and therefore still quite expensive. These drives use flash storage that has no moving parts and is much quicker than a normal hard disk. A popular option is to use both of these storage devices: the solid-state drive for the operating system, which will result in faster boot times, and the larger hard disk for your documents, music, movies, and so on.

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When shopping for a hard disk you can't go wrong with devices from Seagate and Western Digital, while solid-state drives from Samsung, Toshiba, OCZ, Kingston, Crucial and Intel, among others, should serve you well.

Ensure the hard disk speed is at least 7,200 revolutions per minute (RPM), and uses a Serial ATA (SATA) connection capable of speeds of 6GB per second. The solid-state drive you are looking for should be listed with multi-level cell (MLC) flash memory.

Central processing unit

The central processing unit, more commonly known as the CPU, processes hundreds of thousands of commands each minute, and can be considered the brain of your computer. The processor will be one of the most expensive components in your computer, but there a few things you need to understand before you look for the fastest one.

Two companies, AMD and Intel, offer a wide-range of computer processors, both of which have their pros and cons. Intel's chips generally perform slightly better than comparable AMD chips, however AMD's chips are available at a lower price point.


So, what's the best processor?

It all depends on what you are looking for and how much you are willing to spend. AMD chips aren't bad, and are perfect for making sure you don't go over your budget. If money isn't a problem, though, I recommend an Intel processor.

But wait, there's more.

The brand of a processor isn't the only thing to research. Processors are available with a variety of cores and are clocked at different speeds. You may think a faster clock speed means better performance, however, this isn't always the case.

While a quad-core processor will generally perform better than a dual-core model clocked at the same speed, a plateau effect can begin to occur with a higher number of cores. Most games and programs aren't designed to take advantage of more cores; in most cases a hexa-core processor or higher is just overkill.

Things can get more complicated when you look at dated models, for example an old quad-core processor can be outperformed by a newer dual-core model. Before you get caught up in the speed and number of cores a processor has, take a step back and a deep breath.

When shopping for processors you will see something called L3 cache; this is used to store data that the processor needs to access at a moment's notice. The more cache a processor has will only benefit you. Lower-end CPUs usually have 4MB, while mid-tier and higher-end models have anywhere from 6MB to 15MB of L3 cache. A processor with 6MB or 8MB of cache should be more than sufficient for today's games.

To future-proof my desktop, I usually go for the newest CPU model, or close to it. Remember, faster speeds and more cores translate to more money, more heat, and more electricity. A high-end quad-core processor should be more than enough for the latest PC games.


If the CPU can be considered the brain of a computer, the motherboard is the heart and soul. Every component connects to the motherboard, which then pumps commands to others parts of the system.


When choosing the correct motherboard there are certain rules that must be followed: socket compatibility, size, slots, and ports.

Before purchasing your new motherboard you have to ensure that it supports your processor brand (AMD or Intel), and that it is also compatible with your specific processor model. Next, you have to make sure that it will fit inside of your case.

Desktop motherboards come in a variety of sizes, the most popular being Mini ITX, Micro ATX, ATX, and Extended ATX. Each size offers different features, for example a larger Extended ATX motherboard will have more sockets and ports than a smaller Mini ITX motherboard.

Some of the top motherboard brands include ASUS, MSI, Gigabtye, AsRock, and EVGA.

Build your own desktop computer
Watch this: Build your own desktop computer


The second most expensive item on the list will likely be the graphics processing unit, or GPU for short. The graphics card slides into one of the PCI, or Peripheral Component Interconnect, slots on your computer's motherboard. When shopping for a GPU there are three options to choose from: NVIDIA, AMD, or integrated.

Both NVIDIA and AMD produce consumer-level graphics cards, and similar to the Intel versus AMD processor battle, both brands have their pros and cons.

Sarah Tew/CNET

If you have a high-end processor there is also a good chance it includes an integrated GPU, such as Intel HD Graphics or AMD Radeon HD. While these cards are sufficient for basic Web browsing, word processing, and video streaming, they won't perform nearly as well as a discrete graphics card.

NVIDIA and AMD are on par with each other in terms of graphics and power. In fact, with each new card, NVIDIA will leapfrog AMD, and vice-versa. AMD also offers cards with 3GB of RAM, which tend to perform better when using multiple monitors, and their cards are usually slightly more affordable.

GPUs are available with a range of options, including 1GB, 2GB, 3GB, and 6GB of RAM. As mentioned above, the more RAM a graphics card has doesn't necessarily mean it will perform better. RAM is most useful when using multiple monitors, if you won't be doing this than you skip that 6GB card and save yourself a good chunk of money. Cards with 2GB or 3GB of RAM should be plenty for high-end gaming.

It should also be noted that just because you may use an AMD processor, it doesn't mean you have to use an AMD graphics card. The only requirement is that your motherboard has the proper socket for your card, most likely PCI Express or PCI.

Personally, I prefer an NVIDIA card over AMD when it comes to high-end gaming. NVIDIA's cards include a technology known as PhysX, a physics engine that is used in many new games, that makes for a more dynamic gaming experience.

Some popular GPU manufacturers include EVGA, Sapphire, MSI, and ASUS.

Random-access memory

RAM, or random-access memory, is quickly accessed by your computer to perform tasks while a specific program is running. RAM cards plug directly into the memory slot on the motherboard and are available in three different speeds: 1,330MHz, 1,600MHz, and 2,400MHz.

Motherboards have a different number of memory slots, some have only two and others can have up to six. Before buying your RAM, check how many slots your motherboard is equipped with and what speeds it supports.

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The difference in RAM speeds is minimal, especially when going from 1,330MHz to 1,600MHz. You will see somewhere around a 4% performance boost when upgrading from 1,600MHz to 2,400MHz, however the cost usually isn't worth the small increase.

Most of today's games can run fine on computers equipped with 8GB of RAM. Upgrading to 12GB or 16GB can help future-proof your system, but anything higher is just overkill. Be sure that the RAM is also listed as DDR3, which is the fastest type available, with 240-pin being the most popular.

There are hundreds of RAM manufacturers out there, some of my favorites include Corsair, Mushkin, Kingston, Crucial, and G.Skill.

Power supply

The power supply transforms the electricity from your wall socket to give life to your system and all the components inside of it. Companies that offer pre-built computers like to skimp on the power supply in an effort to lower prices and offer more affordable devices, however this is not advised. A power supply that is underpowered could short your system and cause irreversible damage to those expensive components you just bought.

Power supplies are offered in modular and non-modular configurations. Modular models include cables that are detachable, requiring only the ones you will use to be connected to the device. A non-modular unit has all the cables connected to the power supply, regardless if they will be used or not.


An example of a modular power supply.


Modular setups tend to be more expensive, but the payoff is less clutter and better air circulation throughout the case.

The next thing you need to look at is efficiency. Power supplies are rated through a voluntary certification program known as "80 PLUS." Ratings are issued on a scale of Bronze, Silver, Gold, and the highest efficiency of Platinum. You may occasionally see companies label power supplies with other ratings such as "85 Plus," however, these are not official standards. The power supply on my personal desktop computer has a Silver efficiency rating.

The last step is calculating the proper wattage your system requires. Not enough power can result in malfunctions and damage to the hardware, while too much is a waste of money. To be exact, you must measure how much power each component requires and add the totals together. An easier way to do this is to use one of the many online power supply calculators (here are two good ones from Newegg and ASUS).

Some popular power supply brands include Seasonic, XFX, Antec, OCZ, Corsair, and Enermax.

Optical drives

With the rise of cloud services and digital downloads, optical drives are becoming less of a requirement and more of a luxury item. You will need a CD-drive to install your operating system, but other than that I rarely use mine. For the best experience, I recommend a Blu-Ray/DVD/CD drive, which will turn your computer into a home entertainment system.

Wireless card

For Internet access, you will need to plug an Ethernet cable directly into your computer, attach a wireless card to the motherboard, or use a wireless USB dongle. The option is up to you, an Ethernet connection is faster than wireless, while a wireless connection is gives you more freedom, that is unless your modem is close by.


A wireless USB dongle plugged into the ports in the back of a computer.

Sarah Tew/CNET


Cases come in a variety of sizes and finding the right one is always a difficult process. You want a case that is big enough to fit your components and any future upgrades you may purchase, but you also want one that has excellent air flow and expresses your personality to the fullest.

One thing you must pay attention to is the size of your motherboard. Your case has to be compatible with the motherboard you decide to buy, whether it is Mini ITX, Micro ATX, ATX, or Extended ATX.


Most cases have at least one front-facing fan that is included, as does the processor, graphics card, and power supply. You will be required to purchase a few others, however, to ensure your system won't overheat.

The amount of fans required differs based on the size of your case and the components inside of it, but there is usually an intake fan in the front and on the side, and an outflow fan on the back and top of the case. Fans are available in a range of colors and give you the freedom to provide a unique look for your computer.

When purchasing fans, be sure to buy the correct size for your case.

LED lighting

What better way to set your computer apart than to add custom LED lights. This is purely a cosmetic move and is completely optional, but it is, at least in my opinion, a great way show off your hard work and the dedication you spent building your new computer.

Operating System

All those shiny new parts are no good without an operating system. Nearly everyone reading this will choose some form of Windows, although another (and free) alternative is one of the many Linux-based operating systems such as Ubuntu. These can be more complex than Windows, in addition to having fewer compatible programs and games available than Microsoft's operating system.


Another choice you must make is between Windows 7 and Windows 8. I prefer the look and feel of Windows 7, but that is just a personal preference. I would also avoid OEM or "Builder" versions of the operating system, as they can only be installed on one PC. Make sure you purchase the 64-bit version and not 32-bit, which has limitations on RAM.

Where to buy

One of my favorite places to shop for computer parts is Newegg. I have been using the site for years and have had nothing but pleasant experiences with their unmatched customer service. I am also lucky enough to live near a Micro Center, which offers everything you need, and more, to build your own computer. Other sites such as TigerDirect, and even Amazon, have a great selection of parts.

I cannot stress enough the importance of reading customer reviews and doing proper research. Building your own computer and buying the right components should not be something you do on a whim. Before you spend hundreds of your hard-earned dollars, make sure you know what you are doing.

If you have bought all your parts and are ready to set things up, check out part three of our guide to building your own computer.

If this all seems a little above your skill level, remember there's no shame in buying a new computer. Scan our lists of the best laptops and best desktops you can buy right now. We won't judge.