We publish a plethora of PC build guides here at PCWorld. In the past few months alone, we've covered how to build a quiet, energy-efficient PC, how to assemble a powerhouse Sandy Bridge-E computer, and how to put together a compact gaming machine and a compact energy-efficient system. All of those articles follow a certain theme and deal with the component selection and performance levels of the systems.

This time around, we're taking a different approach. In this piece, we're going to look at system building from a nuts-and-bolts perspective and outline some of the most common problems that can arise when you're assembling a PC. While it is true that most computer components can be installed in only one way, or fit in only one type of slot, the process involves some subtle nuances that only experienced PC builders know to watch out for.

With that in mind, here are some of the issues that are most likely to crop up when you're installing processors, heatsinks and coolers, motherboards, memory, graphics cards, drives, and power supplies. Print this article out and post it near your work area to ensure that you always have access to basic PC building best practices.


Installing a processor is straightforward: Processors are keyed to fit into a socket in only one direction, and they don't require tools to install. A few things can go wrong, however.

First, it's important to ensure that the processor's socket is clean and free from dust or debris. If the socket has any foreign matter that could prevent the processor from seating properly, significant problems could occur. Before placing the processor into its socket, give the socket a thorough physical inspection (without touching any contacts) and make certain that the socket has nothing in it that could interfere with the processor. Proper seating and alignment are of the utmost importance when you're installing a CPU.

With AMD processors, it's also vitally important not to bend any pins. Intel processors use a different type of packaging and don't have pins on their underside (the pins are in the socket), but AMD chips still have hundreds of delicate pins that are relatively easy to bend. When handling an AMD CPU, grasp it from the sides only, inspect its underside to confirm that no pins are bent, and use minimal force as you insert it into the socket. In fact, an AMD processor should just drop into its socket, provided that all of the pins are aligned properly.


When new system builders attempt to install CPU coolers or heatsinks, they tend to make three mistakes: They use too much (or too little) interface material, they seat the cooler improperly, or they point the cooling fan in the wrong direction.

Before installing a CPU cooler, make sure that the chip's integrated heat spreader and the cooler's base are clean. Afterward, it's important to apply a high-quality thermal interface material. TIMs help facilitate heat transfer from the chip into the base of the heatsink. Using too much or too little TIM can hinder the heat transfer, however. Use just enough to cover the processor's integrated heat spreader with a paper-thin layer. A dab a little larger than a BB but smaller than a pea will do.

In addition, it is critical to confirm that the cooler or heatsink is seated properly and making good contact with the CPU. Make sure that there's nothing surrounding the socket area that could interfere with the cooler, and when you're positioning it over the CPU, check that it is seated perfectly flat. If a CPU cooler is even slightly off-kilter, the processor is likely to overheat and take damage.

If you have a tower-type cooler, it's also crucial to mount the cooler in such a way that its fan blows air through the heatsink fins, toward the exhaust fan. Typically that means pointing the cooler's fan in the direction of an exhaust fan at the rear or top of the case. Pay special attention to the design of your particular case, though, as some rear-mounted fans are actually intakes.


Installing the motherboard is one of the more tedious tasks when you're building a system. It's relatively simple, but it requires installing a slew of standoffs and screws, in just the right location. And when something goes wrong, pulling out a motherboard can be a real pain, especially if you're almost done with the build and have to rip out a bunch of expansion cards too.

Before installing the motherboard into the case, you should almost always take care of two other tasks first: installing the motherboard's custom I/O shield, and mounting the CPU and cooler. You can't put the I/O shield in place once the motherboard is mounted, so install it before locking down the mobo. And if your case doesn't have the proper cutouts in its motherboard tray to allow for CPU cooler installations on an already installed motherboard, handle that job before installing the board too.

Some of the most common issues that new system builders face relate to the brass standoffs included with most cases. Brass is a relatively soft metal, so stripping the threads on the standoffs is somewhat easy. Be sure to use only enough force to keep them snug against the motherboard tray; finger-tightening is usually sufficient. Use caution when installing the screws that hold the motherboard in place into the standoffs, again to avoid stripping the threads. Tighten the screws just enough to hold the motherboard without causing vibration; there's no need to crank them down and put undue pressure on the motherboard.

Also, use only as many standoffs as your type of motherboard requires. If you have any additional standoffs underneath the motherboard that don't line up with screw holes, remove them. Extra standoffs underneath a motherboard can cause a short or eventually wear their way through a trace and damage the board.

MemoryMemory is one of the easier components to install in a system. Provided that you have the correct type of RAM for your rig, it will be keyed to fit into the memory slots in only one way. Before doing anything, however, consult your motherboard's manual to determine the correct memory slots to use. Most current systems require double-, triple-, or even quad-channel memory configurations to achieve optimal performance, and the memory sticks must be installed in the correct slots to ensure multichannel operation. If you install the memory in the incorrect slots, the system will probably still boot, but it may operate in single-channel mode, which will affect performance adversely.

Another thing to consider is the height of the memory sticks. Many high-performance modules have relatively tall heatsinks that may not fit in some compact enclosures or underneath aftermarket CPU coolers that overhang the memory slots.

Next Page: Installing Graphics Cards, Drives, Power Supplies, and Case Components

Graphics Cards

Although installing a graphics card is also a fairly straightforward process, you should keep a handful of things in mind. Virtually all new graphics cards available today are designed to be used in a PCI Express x16 slot, also known as a PEG (PCI Express Graphics) slot. Many motherboards have multiple physical PCIe x16 slots, yet not all of those slots have true x16 electrical connections to the chipset. Typically you should install a graphics card in the uppermost PEG slot (closest to the CPU socket) to ensure optimal performance. If you're uncertain about which slots on your motherboard best support graphics cards, consult the motherboard's manual to see which slots are true x16 slots.

Many of today's higher-end graphics cards also require supplemental power connections. Be sure to use a power supply with enough capacity to support your graphics card, and remember to connect the necessary supplemental power leads before turning on your system. If the required power leads aren't connected, the system may refuse to boot or to show any video.

Look out for memory slots that fall too close to the graphics card, as well. When the retention clips on the memory slots are closed, they should be out of the way. But if the retention clips are in the open/lower position, they may stick out far enough to make contact with the graphics card and possibly shear off a surface-mounted component.

Drives and Storage

Installing drives into a system is usually a simple procedure, but you should remember a few things to ensure optimal placement and easier cable management.

Depending on the size and type of the case you're using, typically you'll mount the hard drive in a cage that sits behind the expansion slots. If the drive slides into the cage perpendicular to the motherboard tray, it's usually best to have the drive's connectors facing the back of the system, so that you can run cables behind the motherboard tray. If the drive slides into the cage parallel to the motherboard tray, though, be sure to choose a location that won't encroach on any expansion cards. With many smaller midsize towers and minitowers, installing a hard drive into the wrong location will interfere with longer expansion cards, such as graphics cards.

Power Supplies

Few things can go wrong when you're installing a power supply. Most cases have a single location for mounting a PSU, and the associated mounting holes are keyed to allow installation in only one way. Just be sure to fasten the power supply securely, because it is most likely the heaviest component in the system. Use a unit that supplies ample power for all of your components, too. In fact, it's best to allow for future expansion--if your components require 350 watts, for example, springing for a 550-watt (or somewhat larger) PSU is advisable. Also, stick with a reputable brand; off-brand power supplies rarely meet their advertised specifications. A good power supply is critical if you intend to build a reliable, stable system.


Few cases require assembly, but you still have a couple of chassis-related issues to watch out for when you're putting together a system. First and foremost, be extremely careful when removing drive-bay covers to accommodate your drives. Many cases have metal knock-outs that you need to remove before you can install an optical drive or a bay-mounted device such as a fan controller. These knock-outs, and the small metal tab left behind after you remove them, can be extremely sharp. (Take my word for it--I once required 12 stitches after suffering an unfortunate accident while building a system for a friend a few years back.) Use gloves if you'd be more comfortable.

Another annoying issue involves the case wiring. Installing the tiny connectors for the power/reset switches, the speaker, and the activity LEDs can be a real pain, especially since there isn't a standard layout or easy color-coding. Consult your motherboard's manual for the correct front-panel connector layout, and keep in mind that the white wire in most connectors is usually the negative (-) lead.

Great work! We've covered many of the most common PC building pitfalls here; with so many hardware combinations available, however, countless other issues can arise as well. If you've encountered problems that we didn't cover, share them in the comments area below.