How to Build a PC from Scratch: Step-by-Step Beginners’ Guide

Learning how to build a PC is daunting, but piecing all the components together is easier than it may look. For the most part, building a computer boils down to knowing where to plug in your components and cables. In this guide, we’re going to walk you through the process of building a computer step by step, regardless of your background or experience.

If you are already familiar with the overall process of building a PC, you can jump to a specific step using the list below:

Getting started

This guide is all about piecing components together to create a functional machine. If you haven’t selected and purchased all the required hardware, make sure you do that first. It’s also a good idea to purchase (or craft) your case last so you can make sure everything will fit inside it.

Have your parts? Good. Let’s build a computer!

There are a couple of safety issues to discuss before we actually start ripping open those boxes.

Safety first

There’s an invisible risk when building a computer that can crush the most powerful system: Static electricity. The same force that lets you shock your friends when you wear wool socks can also fry components in a heartbeat. Fortunately, static is easy to all but eliminate with a few simple steps.

One simple solution is to purchase an anti-static wristband. One end wraps around your wrist, and the other clips somewhere on the computer case, keeping the wearer constantly grounded. Touching the case frequently with the PSU plugged in and powered off achieves the same effect.

This guide serves as a general overview of the process, and the instructions packed with your parts may vary from our suggestions. When they do, default to the included instructions and use our guide as a road map for the overall project.

Opening the case

Preparing the case is the easy part. Instructions for the specific case you purchased should introduce you to its basic layout as well as list special instructions regarding component installation.

Lay down the case in your work area and remove the side panel. For most PC cases, this means the left-side panel when viewed from the front. This panel provides access to the case interior.

Also, remove anything that’s dangling inside the case. If it’s attached, push it aside. Many cases have permanent internal wiring that becomes problematic later on.

Before we start putting everything together, we’ll first install the power supply and then set the case aside for a few minutes.

Step 1: Install the power supply

The first component to make its way into the case should be the power supply (PSU). It is typically located at the rear of the case, usually in the bottom or top corner.

When in doubt, the slot is easily located by searching for a square opening with screw holes in at least two corners. The PSU sits in this opening with its power switch and a female socket facing out from the case’s back panel. Consult your case’s manual if you have trouble finding the proper location.

You can install the power supply with the fan facing up or down. In most computer cases, pointing the fan down is ideal. All you need to do is look at your case. If there’s space between the bottom and floor (and preferably a dust filter in between), install your power supply with the fan facing down. Most modern cases are built for this type of installation. If your case manual says something different, however, we recommend following that.

There are two main power supply variants: Standard and modular. There’s a hybrid semi-modular type too, but we don’t need to worry about that for now.

Modular PSUs have cables that detach from the main unit to avoid clutter. They’re ideal for smaller cases and neat freaks. If you have a modular PSU, it’s best to leave the cables out for now and run them as you install each additional component.

If the PSU’s cables don’t detach, carefully bundle them so they’re hanging out the case’s open side panel. This temporarily keeps them out of the way while we install the remaining components.

Step 2: Install the processor

Next, prepare the motherboard by installing the CPU and RAM before fitting it in the case. They’re a lot easier to install now rather than after the motherboard resides in the system.

In fact, depending on your case and cooler, you may not be able to assemble your system with the motherboard already installed. That’s because many after-market coolers use a backplate to provide the tightest fit possible. It is, of course, attached to the back of the motherboard. You won’t be able to install it unless you have a case with a cut-out that aligns with the backplate’s location, a feature typically found only in high-end enclosures.

Carefully remove the motherboard from its anti-static bag and set it on a hard, flat, non-metal surface such as a wooden desk, or the top of the motherboard box itself. Also, make sure there are no sources of dust or liquid nearby.

Even though installing a CPU is an easier task now than it was in previous years, it’s still one of the most precarious. There are numerous pins on the CPU and motherboard, and bending any one of them could render that component kaput.

That said, the process isn’t designed to be difficult, and as long as you follow the instructions clearly and keep an eye out to ensure the chip is fully seated before you clamp it in place, you’ll be fine. However, there are some subtle differences in the process depending on who made your CPU.

How to install an Intel processor

Instead of jutting from the processor, pins now reside in modern Intel sockets on motherboards, making CPU installation easy. This part of the socket is called the contact array. Absolutely do not bend or touch these pins!

The square metal bracket holding the CPU in place is the load plate, and it’s raised and lowered using the load lever. When clamped down, the end of the load lever tucks under a hook to keep everything in place. When you unbox your motherboard, the contact array will be covered with a piece of plastic. This plastic will pop out once you open the bracket, so wait to open it until you’re ready to install your processor.

First, open the load plate. Do this by gently pushing down on the load arm and moving it out sideways from under the hook, and then raising it up all the way. The hook’s lever action opens the plate, which you can easily flip up. At this point, the plastic piece will come loose. If it doesn’t pop out, gently remove it.

As shown above, the CPU itself should have a small half-circle notch on each side of the chip. With the contacts facing down, there should be only one direction where the notches line up with the notches in the socket. Pick up your processor by the sides, clamping it lightly between your fingertips. Here, you want to avoid touching the bottom of the processor.

With the processor in hand, line up the notches (or use the small gold triangle in the corner to line up the socket) and set the processor in. You don’t need to apply any force here. The processor should slot in without issues. Once it’s sitting in the socket, very gently press the side to make sure it’s slotted in. Again, very gently do this. You don’t want to move your processor. You want to make sure it’s in place.

Use the load arm on the side to lower the plate over the chip, then push down and re-clip the arm under the hook once again. This requires a fair amount of pressure, so make sure the chip is properly seated before pressing down.

Remember, the notches in the processor should align with those in the socket. If in doubt, start again and double-check.

How to install an AMD processor

Unlike Intel’s design, pins jut from AMD’s CPUs. These pins insert into holes embedded in the motherboard’s CPU socket. The load arm on the socket slightly shifts the holes underneath, gripping the pins on the processor when pressed all the way down.

If it isn’t already, raise the arm so that it’s pointing straight up, and then rests a little farther back. That ensures the holes for the pins are wide open.

Instead of using notches, correctly line up the processor in the slot using a triangle engraved in gold on one of the CPU’s corners. All you need to do is line that triangle up with a second triangle cut into the slot. Again, pick up the processor by the sides gently, avoiding the bottom.

Once the processor sits comfortably in the slot, simply press the arm down until it clicks into place and locks in. This last step can be intimidating since it requires a fair amount of pressure to lock in place.

Step 3: Install the RAM

System memory, or RAM, doesn’t require any careful goo placement or wires. There are just two important factors, assuming you’ve chosen compatible RAM: Direction and slot choice.

The direction is easy enough. Each memory stick has a notch in the contacts lining the bottom edge that lines up with a block in the motherboard’s memory slots. If you hold it just above the slot and the two line up, it’s facing the right direction. If it doesn’t line up, spin it 180 degrees.

Slot choice depends on a few factors, one of which is how you purchased RAM. If it’s just a single stick, install it in the A1 slot and move on with your life. A diagram in the motherboard’s manual should label the slots if it isn’t printed directly on the PCB.

However, you likely purchased two identical RAM sticks, a common package called a dual-channel configuration. The system can use both sticks as if they were a single block of RAM but accesses them individually, providing a modest boost to memory performance.

You should install these sticks in channels (slots) with matching colors, usually labeled A1 and B1, though sometimes A2 and B2 are preferable. Check your motherboard’s manual to confirm which are best for your system.

Now that we know the proper slot and direction, the next part is easy. Push the plastic wings at either end of the slot down and outward (some motherboards only have one) then place the stick in the slot sticking straight up. Push down firmly until the RAM clicks into the slot, and the plastic wings click back in and clamp the ends of the sticks.

We put together a more detailed guide for how to install RAM if you need additional information.

Step 4: Install the motherboard

Installing your packed motherboard is easy enough, but it can’t just sit in your case. Most modern cases have built-in, non-removable spacers between the back wall and motherboard, known as standoffs. They act as a ground for the motherboard while preventing the connections on the back from shorting.

Some cases have removable stand-offs you must manually install. They’re easy to identify because they look unusual — essentially screws that have another screw hole on top instead of the typical screwdriver notch. They’re usually copper or gold in color, making them easy to pick out.

If not, you may need to wiggle the motherboard slightly to make sure it snaps properly into the I/O shield and the stands-offs align. This may require some effort, but it shouldn’t require much force. If you’re forcing the motherboard, double-check how it’s aligned, as it may not be properly positioned. Be firm but gentle.

Depending on the case and motherboard combination, pairing the two requires between six and 10 screws. You may find that not all holes match up with standoffs underneath. Drop a screw into a hole to see if it threads right away.

Like every set of screws, the first step is seating the screws and giving them a couple of precursory turns. Then, proceed in a star pattern, tightening each screw a little at a time. Don’t go wild while tightening as you might damage the board. You only need enough torque to hold the board in place without wiggling.

Once the motherboard seats comfortably in the case, there are a few necessary connections.

First, the motherboard’s power connection is a wide, two-row cable that fits snugly into a similar looking spot on the board itself. This 20-28 pin connector powers both the motherboard and the CPU. However, some boards have a second 4-pin or 8-pin connector for the processor, which resides near your CPU, typically in the top corner. If you have it, you’ll need to plug that in, too.

Second, connect the case plugs and buttons to the motherboard. A double-wide row of pins — the location of which will be noted in your manual — runs the USB ports, buttons for reset and power, and activity LEDs for power and storage.

These small cables run in a bundle from wherever the ports reside in the case. Proper installation can be difficult, however, due to their size. If you have a magnifying glass or a set of tweezers, now is a great time to use them. Some motherboards include an adapter that bridges these jumpers to the right connections on your motherboard. Otherwise, installing them is as simple as matching the labels on the pins with the labels on the connections.

The USB header connecting to your front-facing motherboard ports will be on its own. This connection is around eight by two pins, and they’re enclosed in a larger plastic housing. This header has a notch on one side that should clearly indicate which direction it plugs in.

Step 5: Install the CPU cooler and/or heat sink

With the motherboard now tethered to your case, you can wipe the sweat of concentration off your brow. Now it’s time for the CPU cooler or heat sink!

Installation is simpler when using the CPU’s packaged cooler. The process varies, however, given the different brands and generations. You’ll need to refer to the included instructions for specific details. The same is true for third-party coolers, which use a proprietary installation bracket. Following the included instructions is crucial to your PC-building success.

Every cooler needs thermal paste. It’s an excellent thermal conductor, allowing heat to transfer from the chip to the cooler with ease. Without it, your cooler won’t work very well, if at all. If you aren’t sure what type of thermal paste to use, it’s well worth doing some research, and we have a list of the best thermal pastes for you to choose from, too.

AMD and Intel apply it to their coolers in the factory, but third-party coolers require manual pasting. Unfortunately, rubbing goo on an expensive CPU isn’t as straightforward as it sounds.

When directed by the instructions, simply apply a single silver dot — about the size of a small pea — right in the center of the chip. After squishing the chip and cooler together, try not to wiggle or twist too much, to ensure a smooth, full connection. If you’re using your own thermal paste instead of what’s pre-applied, make sure to fully clean the cooler using coffee filters with a little bit of isopropyl alcohol, removing any trace of the previously applied paste.

For basic heat sinks, you’re now finished; just wait for the paste to cure. But the full fan system still needs power. Plug the wires from the fan into a four-pin connection on the motherboard, which should be close to the processor and labeled “CPU_FAN.�

Step 6: Install your graphics card

Not every system needs a dedicated graphics card (discrete GPU). If you want a stand-alone chip for graphics, like PC gaming, installation couldn’t be simpler. We’re also assuming for this step that the card you chose is appropriate for your case size, capabilities, and power supply.

Modern graphics cards use a PCI-Express (PCIe) x16 slot. It’s a long, thin connector located on the rear of the motherboard, below the processor. For the vast majority of motherboards, you’ll want to use the top PCIe x16 slot.

To seat the card in that slot, you’ll need to remove a rectangular backplate from your enclosure. It’s one of many thin metal brackets lined down the back of the case to keep it sealed up.

You’ll need to remove one or two, depending on the card’s width. Do this by removing the screw that secures the backplate to the chassis. Once removed, the plate should slide (or fall) out freely. Keep the screw as you’ll need it in a moment.

After removing the brackets, make sure the switch on the motherboard’s PCIe slot is pushed outward. Then, with the ports facing the empty spot where the backplate used to be, carefully line up the long series of contacts on the card with the appropriate slot on the motherboard. Once it’s lined up properly, a solid push on the top of the card should cause it to snap into place as the switch clicks back in to hold it.

You don’t need excessive force, but if you encounter a great deal of resistance, take another look at the backplate and PCIe slot to make sure both are clear and the motherboard is properly aligned. Also take note if there is a push-pin that locks the card in like your memory slots, as some motherboards use it as a safety measure.

Use the screws pulled from the metal brackets to fasten the back of the card into the same spot in the case. Again, they don’t need to be extremely tight — just enough to hold the card firmly in place.

The connector is designed to prevent improper installation, so if the connection isn’t easy, double-check your alignment to make sure it’s correct.

Most video cards need extra power apart from what the PCIe slot provides. If your card needs extra juice, you’ll see a PCIe power connector on the card’s side facing away from the motherboard or, in some cases, on the side facing the front of the case. This connector is a group of square plastic pins numbering six or eight.

The most powerful cards may have two such connectors. Find the appropriate connector on your power supply, typically labeled VGA, and slot it in. The connector’s design prevents improper installation, so if the connection isn’t easy, double-check your alignment to make sure it’s correct.

If you need additional help, we have a detailed guide on how to install a graphics card with additional information.

Step 7: Install any additional expansion cards

Graphics cards aren’t the only components that use PCIe slots. Other add-in cards include wireless networking, sound, video capture, and even storage. Their installation is no different than adding a discrete GPU.

First, remove the metal bracket in the back of the case that corresponds with the PCIe or other expansion slot playing host to your add-in card. Keep the bracket screw handy so you can use it to secure your new card.

PCIe slots have a small switch at the interior end, which you push down and outward to open the slot. After that, line up the row of contacts on the card with the slot and firmly push down. Once you properly seat the card, the switch flips up. Securing the card in place is as simple as screwing it into the back of the case and attaching any necessary PCIe ports.

There are a few different types of PCIe slots. Many expansion cards use the “PCIe 4x� slot, which is much shorter than the full PCIe slot used by video cards. A quick check of your motherboard’s connectivity, and the size of the connector on your card, will make it obvious which slot is appropriate. If in doubt, refer to the expansion card’s manual.

Step 8: Install your storage drives

There are three different storage drive sizes you’re likely to encounter, and they all mount and connect differently. Generally, hard disk drives (HDD) are the larger 3.5-inch size, while newer solid-state drives (SSD) adopt the smaller 2.5-inch size. There’s also the even smaller M.2 format and PCI-Express drive format, which tend to be thin sticks with bare chips measuring around 1 x 3 inches.

We’ll start with 3.5-inch data drives, which are usually mounted up high at the front of the system. Your case is almost guaranteed to have at least one slot dedicated to this drive type. Installation depends on the enclosure, however, as most cases have a simple hard drive cage. Installing a drive means slotting it into a mount on the cage and aligning the screw holes on the drive’s sides with those on the cage. Make sure the drive’s power and data connectors face inwards, toward the motherboard. Once aligned, screw the drive into place.

Modern cases quite commonly enjoy a “tool-less� installation system. As the term implies, this design should mean it’s possible to install the drive without a screwdriver. Usually, this means placing the drive into a cradle or cage that slots into the case. Refer to your enclosure’s instructions for specifics, since the technique varies from one brand to the next.

For 2.5-inch drives, the mounting process and location vary. Some cases have a cage, similar to the 3.5-inch mounting, where the SSD can just slide in — no rivets, screws or brackets needed. If it doesn’t, the SSD requires an adapter so it can sit securely in a 3.5-inch bay.

You can mount this drive in one of two ways. Either the larger bracket provides holes inside so you can screw the drive into the middle, or the case includes a bracket that adds extra girth to the 2.5-inch drive.

Hard drives require two connections as well: One for power and one for data. The good news is that both are L-shaped, so it’s hard to plug them in the wrong slot or the wrong direction.

For those with a newer M.2 drive, you’ll want to look for a small slot that matches the width of your stick-shaped drive, and a screw located a few inches away. Remove the screw, insert the contact end into the slot, and then push down gently until you can use the screw to hold the drive in place once.

Finally, you can mount PCI-Express storage drives just like you do with graphics cards in an available PCI-Express slot.

Step 9: Make the final connections

Before you get too excited and hit that power button, it’s worth running back through the system to make sure everything is properly seated and connected. Let’s start with the components.

The motherboard is usually easy to spot if it isn’t plugged in. Most PSUs have one wide cable that’s obviously intended for this slot, with no other connections attached. It should plug into your board somewhere near the PCIe slots, but the location will vary.

Your motherboard is also likely to have a second, four-pin (or eight-pin) connector that powers the processor. You may need to look through your power supply’s available connectors with a keen eye to find it given it resembles a PCIe power connector. But don’t worry — a PCIe connector won’t fit, so improper installation isn’t possible.

The CPU cooler also needs power, but that flows from the motherboard. Its power cable doesn’t need to go far, as most motherboards keep the plug close to the socket. The little wire is just three or four sockets and connects to a set of four pins on the motherboard.

The hard drives need power too in the form of L-shaped SATA connectors (unless it’s a PCIe drive). Typically, a string of three or four lines run straight from the power supply using unique connectors. You can’t install them the wrong way, either.

Finally, high-powered graphics cards need dedicated power connections, usually in the form of a black rectangular connector with six or eight pins. Some cards, like the new RTX 3080, even require two eight pin connections. These plugs are brightly colored and easy to spot and only fit in the interior end of the card in one orientation. If they aren’t plugged in, the fans on the card won’t spin, and it won’t produce any video output.

Step 10: Power on

Now that you’ve double-checked everything, switch on the power supply and press the power button on the front. A lot of systems don’t boot correctly the first time, so don’t get discouraged if you need to go back and check connections again.

Once it does boot, you’ll need to install an operating system (OS). Luckily, we’ve built a handy guide that clearly walks you through the process. If you don’t have another PC around to download the ISO, you can purchase a USB thumb drive from Microsoft with the OS image ready to go.

After that, you may need to install drivers. Windows 10 already supports modern chipsets and automatically downloads and installs the remaining drivers in most cases. Check the Update & Security menu in the Settings pane for more information regarding this process.

If that doesn’t work, the chipset driver for your motherboard will handle most connectivity and onboard features, though this varies greatly based on motherboard and component manufacturers. Remember to check component boxes for install discs and other information before throwing them out with the trash.

Typically, only discrete graphics cards require you to manually download and install the latest driver. Check out the AMD page for Radeon drivers or the Nvidia page for GeForce drivers.

With some luck and a lot of attention to detail, you should have a fully operational system. Make sure to keep an eye out for any error messages, and hold your hand outside the case fans to make sure air flows and isn’t too hot — at least for a few weeks.

If something breaks or needs an upgrade, you’re fully equipped to deal with it. Just watch out for static.

After you’re done building your computer, you’ll be left with a mess of boxes, unused cables and connectors, and discs. Keep the boxes or throw them out; the choice is yours. However, we would recommend keeping your extras organized. As you upgrade your computer, a fan-splitting cable or some extra thermal paste will come in handy, and you’ll find these frequently bundled with CPU coolers and motherboards.

Editors’ Recommendations