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 | |||||
|---|---|---|---|---|---|
| Type | Full Tower | Mid Tower | Mini Tower | Mini Cube | Desktop |
| Height | 21-24 inches | 17-19 inches | 12-14 inches | 7-9 inches | 3-7 inches |
| Width | 6-8 inches | 6-8 inches | 6-8 inches | 8-9 inches | 14-17 inches |
| 5.25" bays | 4-9 | 3-6 | 1-2 | 1-2 | 1-3 |
| 3.5" internal bays | 6-12 | 2-6 | 1-2 | 1-2 | 2-4 |
| Motherboard Form Factor | ATX, EATX | ATX | microATX | mini-ITX | ATX, microATX |
| Card slots | Seven | Seven | Four | Two | 2-7 |
| Power supply | PS/2 or larger | PS/2 | PS/2 or SFX | SFX or TFX | Various |
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.
- Step One: Size Up A Case
- Step 2: Select Your CPU
- Step 3: Select Your Graphics
- Step 4: Select A Motherboard
- Step 5: Select Memory
- Step 6: Select Storage
- Step 7: Select A Power Supply
- Other Components
- Step 8: Choose Your Vendor
- Step 9: Preparing For Assembly
- Step 10: Build The Platform (CPU, Cooler, And DRAM)
- Step 11: Install Motherboard And Power Supply
- Step 12: Install Cables, Cards, And Drives
Cheers!
Cheers!
Wonderful as usual toms.. Appreciate it..
Great article! No doubt this is going to help a lot of folks.
Thanks, guys!
I think you missed a section for "SLI - XFire", but it's great overall. Since its a guide for folks with little to no knowledge, I think it would help them to dispel myths and get some facts over XFire and SLI.
Cheers!
First I put the motherboard into the PC (not fastened) to see where the standoffs are going to be placed onto the case. Also I note what routes I'm going use for my cabling. Then I take the motherboard out and insert the standoffs and port plate into the case. Also I take my case cables (power sw, reset sw, USB, front audio and mic cables and put a twist tie around them all and place them near where they are to be plugged into the motherboard. These cables are easy to lose track of.
Next I place the power supply, and "bay devices" (optical drives, non-removable storage, etc) into the case and have those cables attached and either hanging over the outside of the case or routed behind the motherboard tray. This obviously depends on how you determined the cables will be routed earlier.
Then I take my motherboard, put the CPU, RAM, and cooling system on as much as I can. Then I place the whole thing into the case - usually at an angle at first, leading with the side with the RAM (which is normally going behind the case bays in smaller cases) in first.
At this point it's just a matter of aligning the motherboard with the standoffs and port plate. Plug it all in (including the case plugs which are conveniently out of the way and together).
Power it all on and volia!
Otherwise, it was a good article. People who are uncertain of building their own PCs can learn a lot from it.
The 647W is measured at the wall socket, as the article mentions input power. After taking into account the 85% efficiency of their power supply in this example, the PSU is only outputting 549.95W to the PC components at max load. Adding some headroom they come to the 600W PSU recommendation.
Personally I'd like a little more headroom, but the calculations in the article are correct.
Building your own is great fun, and most serious users should probably give it a try at least once in their lives. Given that, I'd recommend an annual "refresh" of this article, with updated info and re-validated links to corresponding reference articles and resource forums.
A great service to your readers!
I wanted to comment on the power supply part of the article. One is the efficiency and the total cost to use versus the front end purchase cost. A less efficient system will obviously create more total heat as wasted energy. But aside from possibly making someones room rather uncomfortable, it also increases your airconditioning energy use. A good rule of thumb is that an AC system will use 50% of the heat energy. To add the total annual cost, multiply that times the percentage of the year that the AC is on. So your example of a 647W system with 85% PSU would give (550W used):
647W - 550W = 93W at plug
93W * 50% = 47W AC energy
Total Energy (summertime) = 93W + 47W = 140W
If the AC were on the while year and the PC were on continuously, this is about $140 annually, or almost $12 per month added electricity in the summer. If you did the same thing with a cheap 70% efficient system, you get $248 annual cost which is $20.63 per month summertime cost. At a difference of $8, it does not take many months (of continuous on!) to make the more efficient PSU make much more sense.
The other topic I wanted to comment on is ESD. I am an engineer and work with ESD issues everyday. It is a very real an poorly understood issue by many because of the often hidden or delayed failures that it causes. ESD many time causes walking wounded damage without an immediate failure, which finally fails several months later. And if you look at websites sell PC parts, many people complain of DOAs. Many, many DOAs are caused by ESD. Memory, CPUs, motherboards, HDDs, and other sensitive systems are often returned as DOA, driving up the cost of the PC enthusiast market and adding frustration. In research texts, they estimate the global electronic failures due to ESD to be 40-60% of the total failures over product life.
So that little $5 ESD wrist strap is money well spent. Buy one and reduce your heartburn.
Charles
So that little $5 ESD wrist strap is money well spent. Buy one and reduce your heartburn.
Charles
The only problem with wrist straps is that most people don't want to be "tied" to anything. They're a great idea that's really rarely needed. Feel free to say otherwise if you live in the desert.