How To Build A PC: From Component Selection To Installation

A great many of the folks who land on Tom's Hardware are already deeply passionate about technology and PC hardware. But we know that others are looking to learn more. We're an inclusive bunch. So if you've never built your own PC, fear not. Our editorial team does it all of the time, and we're happy to walk you through the steps, starting with picking the right parts.

There's a good chance that, even if you haven't gotten your hands dirty inside of a case, you still have a basic knowledge of the components that go inside. Experienced builders often have their ideal configuration in mind before they choose a case. But even a seasoned pro needs to be sure that everything's going to fit inside the right chassis. And of course, enclosures vary depending on what you want to do with your PC. Home theater systems, all-in-ones, flashy gaming boxes, and business-oriented workstations all have their own requirements.

Traditional cases follow the size categories below. However, more modern designs tend to stray from those well-defined standards in the name of differentiation. Mid-tower designs, for example, are now found in nearly full-tower scale. To make matters more confusing, they can even be referred to as full towers, even if they lack the drive bays inside that used to define the form factor.

Traditional Case Sizes
TypeFull TowerMid TowerMini TowerMini CubeDesktop
Height21-24 inches17-19 inches12-14 inches7-9 inches3-7 inches
Width6-8 inches6-8 inches6-8 inches8-9 inches14-17 inches
5.25" bays4-93-61-21-21-3
3.5" internal bays6-122-61-21-22-4
Motherboard Form FactorATX, EATXATXmicroATXmini-ITXATX, microATX
Card slotsSevenSevenFourTwo2-7
Power supplyPS/2 or largerPS/2PS/2 or SFXSFX or TFXVarious

Full towers were traditionally tall enough to hold two power supplies, though many had a second hard drive rack where you might expect to find the top power supply. The interior space of a full-tower chassis is useful in some configurations; however, most mainstream users (and even most enthusiasts) simply don't have enough hardware to fill it.

A better justification for picking a full tower is that the top bays are easier to reach when the case is sitting on your floor. A modern example of the traditional full tower, Rosewill’s Blackhawk Ultra, is the right-most case in the image below.

ATX mid-towers are usually capable of holding full-sized motherboards, full-sized power supplies, several full-sized optical drives (DVD and Blu-ray burners), and multiple hard drives. Well-designed units like the Cooler Master Storm Enforcer (above-left) are well-suited for gaming and video enthusiasts, simply because they support a greater number of expansion cards and hard drives than smaller units. A comparison of our current case reviews to models from ten years ago show that good ideas stand the test of time.

A majority of cases give you room for seven expansion slots around back. Typically, that's enough for a couple of graphics cards, add-in sound, and even back-panel brackets exposing USB or eSATA connectivity. But let's say you love your games, and you're dead-set on building a system with three or even four graphics cards. Specifically seeking out an ATX case with eight or more expansion slots might be necessary, since high-performance cards have thick cooling solutions that use the case’s slot hole for support and ventilation.

MicroATX mini-towers are nearly as versatile as mid-towers in applications ranging from office workhorses to high-end liquid-cooled SLI-powered gaming monsters because of their less-imposing profile and easier trasportability. Mini-towers typically support one or two optical drives and one or two hard drives, and the microATX form factor supports a maximum of four expansion slots. All of those limitations are acceptable for most users.

Mini-ITX cubes typically support a single expansion cards and only the smallest power supplies, though the slightly-oversized Lian Li PC-Q08 above (center) supports larger parts. Relying mostly on integrated features and capabilities, these space-saving enclosures were once only good as office- and productivity-oriented platforms. Now, thanks to more efficient host and graphics processors, we also have access to ultra-compact gaming machines and home theater consoles. Though you'll commonly see these referred to as “small form factor”, the term form factor is better applied to the mini-ITX motherboard found inside. Variations of the cube aesthetic alternatively support ATX and microATX form factors.

Formerly used to raise small CRT monitors up to eye level on flat desks, today’s horizontal desktop cases are mostly restyled for home theater systems. They range from the gaming-themed mini-ITX Raven RVZ01 (pictured bottom-center, above) to the eight-inch-tall full-ATX pedestals laying on their sides. Many of the slimmer models use special half-height expansion cards, though the model pictured above uses a right-angle adapter (called a riser card) to situate a full-sized graphics card sideways. If expansion is important to you, beware of models that use a custom-sized power supply, as those may not be upgradeable.

Want something smaller? The yellow box above is the most compact unit we’ve tested to truly qualify as a performance-oriented machine. Called the Brix Pro, it holds two notebook-sized memory modules, an on-board mSATA SSD, and a 2.5” notebook drive. Shorter single-drive units are available with similarly scaled-down performance, and Intel even jumped on the tiny bandwagon with its similar-appearing NUC (Next Unit [of] Computing) form factor. Most of these machines are available either as a barebones system (no drives or memory) or a complete PC, and all of them use external, notebook-style power adapters.

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32 comments
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  • AndrewJacksonZA
    "the power supply is actually one of the more important parts of a build"
    Thank you!!

    Or rather, let's do what the cool kids are doing and rather post a GIF:
    https://giphy.com/gifs/the-office-thank-you-michael-scott-1Z02vuppxP1Pa
  • Eggz
    Great piece for a lot of first-time builders. This should have a sticky somewhere on the site so it doesn't get buried :-)
  • jkhoward
    Quote:
    "the power supply is actually one of the more important parts of a build" Thank you!! Or rather, let's do what the cool kids are doing and rather post a GIF: https://giphy.com/gifs/the-office-thank-you-michael-scott-1Z02vuppxP1Pa


    Seriously, not enough people realize how import a good PSU is. I am working with someone is heavily overclocking an i7 and two 970 in SLI as well as 4 SSD and a few hard drives, a bunch of fans, with a 750W PSU.
  • jkhoward
    Also... I am digging the age of some of these images.
  • blackmagnum
    This article brings back embarrassing memories. https://giphy.com/gifs/the-office-thank-you-michael-scott-1Z02vuppxP1Pa
  • alidan
    Quote:
    Quote:
    "the power supply is actually one of the more important parts of a build" Thank you!! Or rather, let's do what the cool kids are doing and rather post a GIF: https://giphy.com/gifs/the-office-thank-you-michael-scott-1Z02vuppxP1Pa
    Seriously, not enough people realize how import a good PSU is. I am working with someone is heavily overclocking an i7 and two 970 in SLI as well as 4 SSD and a few hard drives, a bunch of fans, with a 750W PSU.


    unless i'm thinking wrong, isn't that within the power limits of a 750? im even assuming that each gpu is 300 watts and i know they shouldn't hit that even with the most aggressive of ocs

    granted there is a distinction between a good psu and a bad one, but im just assuming its a good one.
  • chimera201
    Motherboard slots haven't evolved much. Wished every slot was like a USB slot
  • turkey3_scratch
    612443 said:
    Seriously, not enough people realize how import a good PSU is. I am working with someone is heavily overclocking an i7 and two 970 in SLI as well as 4 SSD and a few hard drives, a bunch of fans, with a 750W PSU.


    Your point being... ?
  • renosablast
    Steps 1 and 3 should be combined, and step 2 comes after 1 and 3. You better worry about the CPU and motherboard combo compatibility before you worry about a graphics card.
  • renosablast
    Sorry, meant steps 2 and 4 before 3.
  • Dark Lord of Tech
    I love when you see a $1500.00 build with top quality components and then they have a $40.00 PSU listed with it.
  • Outlander_04
    IMO the very first component selection for a gaming build should always be the .... MONITOR.
    Decisions on where and how to spend the rest of the budget can only be made once you know the resolution , and whether its 60 Hz, 144 Hz or whatever else is available
  • MasterMace
    Gonna throw in my disagreement on the priority, mentioned nice and early in the article. The first thing you pick is never your case. There's 3 things you can decide to be your starting point when building a pc to make it a smooth ride; either, 1. Budget. 2. CPU 3. Graphics. By picking 1 of these 3 things as your starting point, you can have a very smooth build process. Does that mean you buy your case last? No, I've seen plenty of builds where the case arrives first as a way of storing the items, but when you want a solid build, your case is last priority, as it has no impact on your performance and restricts the size of your items.

    Even if you wanted to build an odd form factor, like an itx, you would still pick the cpu or the budget before the case.
  • Thank you for explaining ESD correctly. I have been annoyed with articles over exaggerating about ESD a lot. So just touching something metal can help? Well, next time I think I'll set a PC on my wooden desk instead of the carpet.
  • kunstderfugue
    Quote:
    I love when you see a $1500.00 build with top quality components and then they have a $40.00 PSU listed with it.


    The XFX TS Bronze 550 comes down to $43 ish from time to time and that's a mighty fine PSU to power a single graphics card build.
  • nitrium
    Quote:
    "the power supply is actually one of the more important parts of a build" Thank you!!

    While not unimportant, it gets far too much attention on the forum's here. PSU's are only relatively rarely the cause of issues, and I'll go out on a limb and say that virtually ANY modern 650W PSU (even ultra-cheap China garbage) will reliably power a single GPU and CPU, regardless of model or how much OCing you do to them.
  • Crashman
    269694 said:
    Quote:
    I am working with someone is heavily overclocking an i7 and two 970 in SLI as well as 4 SSD and a few hard drives, a bunch of fans, with a 750W PSU.
    unless i'm thinking wrong, isn't that within the power limits of a 750? im even assuming that each gpu is 300 watts and i know they shouldn't hit that even with the most aggressive of ocs granted there is a distinction between a good psu and a bad one, but im just assuming its a good one.
    You're exactly right. We've been using high-quality power supplies in most of our System Builder Marathon machines, and dual 970s was in one of the builds. The super-high recommendations you see from other sites are a response to most builders using mediocre-quality units.
  • Crashman
    416912 said:
    Gonna throw in my disagreement on the priority, mentioned nice and early in the article. The first thing you pick is never your case. There's 3 things you can decide to be your starting point when building a pc to make it a smooth ride; either, 1. Budget. 2. CPU 3. Graphics. By picking 1 of these 3 things as your starting point, you can have a very smooth build process. Does that mean you buy your case last? No, I've seen plenty of builds where the case arrives first as a way of storing the items, but when you want a solid build, your case is last priority, as it has no impact on your performance and restricts the size of your items. Even if you wanted to build an odd form factor, like an itx, you would still pick the cpu or the budget before the case.
    Exactly wrong. The first thing people do is say "I want a LAN box" or "I want a media player" or "I want a big gorgeous office PC". They're picking a case SIZE when they make those FIRST statements, so size comes first in the discussion.
  • beoza
    Quote:
    416912 said:
    Gonna throw in my disagreement on the priority, mentioned nice and early in the article. The first thing you pick is never your case. There's 3 things you can decide to be your starting point when building a pc to make it a smooth ride; either, 1. Budget. 2. CPU 3. Graphics. By picking 1 of these 3 things as your starting point, you can have a very smooth build process. Does that mean you buy your case last? No, I've seen plenty of builds where the case arrives first as a way of storing the items, but when you want a solid build, your case is last priority, as it has no impact on your performance and restricts the size of your items. Even if you wanted to build an odd form factor, like an itx, you would still pick the cpu or the budget before the case.
    Exactly wrong. The first thing people do is say "I want a LAN box" or "I want a media player" or "I want a big gorgeous office PC". They're picking a case SIZE when they make those FIRST statements, so size comes first in the discussion.


    I have to agree with you on this Crashman. Whenever I go to build a new system for friends or relatives I always ask what they're going for in terms of use. I like to go with the Form follows function principle which is that the shape of a building or object should be primarily based upon its intended function or purpose.
  • Libero
    Quote:
    Gonna throw in my disagreement on the priority, mentioned nice and early in the article. The first thing you pick is never your case. There's 3 things you can decide to be your starting point when building a pc to make it a smooth ride; either, 1. Budget. 2. CPU 3. Graphics. By picking 1 of these 3 things as your starting point, you can have a very smooth build process. Does that mean you buy your case last? No, I've seen plenty of builds where the case arrives first as a way of storing the items, but when you want a solid build, your case is last priority, as it has no impact on your performance and restricts the size of your items. Even if you wanted to build an odd form factor, like an itx, you would still pick the cpu or the budget before the case.

    Quote:
    Sorry, meant steps 2 and 4 before 3.

    It is same meaning as define a purpose and choose a case. When you buy a computer you must know what the purpose for first example for home/office, web browsing, gaming or multi-tasking. Budget also is depend to each person. So it is not CPU or GPU before case.
  • James Mason
    I wish the pictures of PSU weren't just all Corsairs. That leads people to believe that all Corsair PSUs are "good" PSUs, when we know a vast majority aren't, and the ones a new builder are most likely to be definitely aren't.
  • Crashman
    297651 said:
    I have to agree with you on this Crashman. Whenever I go to build a new system for friends or relatives I always ask what they're going for in terms of use. I like to go with the Form follows function principle which is that the shape of a building or object should be primarily based upon its intended function or purpose.

    It is same meaning as define a purpose and choose a case. When you buy a computer you must know what the purpose for first example for home/office, web browsing, gaming or multi-tasking. Budget also is depend to each person. So it is not CPU or GPU before case.
    Yeh, I should have just kept his last statement and deleted the rest before responding:
    416912 said:
    Even if you wanted to build an odd form factor, like an itx, you would still pick the cpu or the budget before the case.
    What he's saying is even if you choose a form factor first, you're still buying the other parts first. Which is a backwards way of saying that the order of the article, form factor first, makes sense...and he still wants to disagree...

    The problem is that one needs keep a general concept of the case in mind when picking the actual components. One can often pick the exact case to fit that concept at the end, but the "Define a purpose" leads immediately to form factor, and chopping the article off there only to come back to case selection doesn't really make sense.
  • Bjorn_2
    I miss one important piece of advice: do not install anyhting but your primary drive before installing Windows. I have recently gone through the nightmare of trying to aggregate Windows onto my primary drive when replacing my SSD for a bigger one. It seems that if you have multiple drives installed, windows will happily use all for various purposes. So feel free to install everything but please, before installing Windows, disconnect your secondary and other drives.