How to build a PC from scratch: a beginner’s guide to building your own desktop computer

Building a PC from scratch might seem like a daunting task. From processors and motherboards to graphics cards and cooling systems, there are many elements to consider. Yet despite all these sophisticated components, assembling a desktop computer is surprisingly simple. In fact, if you know how to handle a screwdriver and are not afraid to plug in a few cables, even beginners can build a powerful PC that can handle the most demanding games and software.

This article will guide you step by step through the entire process of building a computer, from component selection to final installation. You’ll discover everything you need to assemble your perfect PC, from safety precautions to installing each piece of hardware. So if you’re ready to get involved and build your own computer from scratch, read on!

What you need to build a PC

Before you start building your PC, you will need to have selected and purchased all the necessary components. Make sure they are all compatible with each other and fit the case you want to use.

Here are the essential components for building a computer:

• Case
• Processor (CPU)
• Heat sink for the processor
• Motherboard
• RAM memory
• Solid-state drive (SSD) and/or hard drive
• Power supply
• Graphics card

Many of these hardware components must be compatible with each other, which can create some headaches for newcomers. We recommend using a site like PCPartPicker to select your components, as it automatically checks for compatibility.

Before you start, make sure you have a clean and large work space to open boxes and assemble parts comfortably.

Safety first

When building a computer, there is one invisible risk you don’t usually have to think about with an assembled PC: static electricity. The same force that allows you to blow up your friends when wearing wool socks can also damage components in the blink of an eye. Fortunately, static electricity is easy to eliminate almost entirely with a few simple steps.

One solution is to purchase an antistatic wristband. One end wraps around the wrist, while the other hooks somewhere on the computer case, constantly keeping the wearer grounded. Frequently touching the case with the power supply on and off has the same effect.

Also be sure to assemble your PC in a room with a bare floor if possible-carpets generate a lot of static electricity-and wear rubber-soled shoes instead of socks. Many components arrive in anti-static bags, so leave them in these bags until installation.

Opening the case

Getting the case ready is the easiest part. The instructions for the specific case you purchased will present its basic layout and give you any special instructions on installing the components.

Place the case on your work surface and remove the left side panel. This panel provides access to the inside of the case.

Also remove anything hanging inside the case. If it is attached, move it aside. Many cases have permanent internal wiring that can become problematic later.

How to install the power supply

The first component to plug into the case should be the power supply unit (PSU). It is usually located in the back of the case, usually at the bottom, but in some older cases it may be at the top. Consult your case manual if you have difficulty finding the correct location.

1. Most cases are designed to install the power supply with the fan facing downward so it can draw in fresh air from outside the case, but check your manual if you are not sure. You may have to remove a PSU mounting plate depending on your case, but in most cases you will simply have to push the PSU into the rear opening of the case, from the inside.
2. Attach the PSU to your case using the appropriate screws or wing nuts.
3. If your power supply is modular, connect the power cords you need for the various components. If you are not sure, don’t worry, you can connect them later as you need them. If your power supply is not modular, you will have all the cables already installed.

How to install the processor

Although it is not mandatory, it is a good idea to install the processor before inserting the motherboard into the case, as access will be much easier.

1. Gently remove the motherboard from its anti-static bag and place it on a flat, hard surface, such as a wooden desk or the top of the motherboard case itself.

The process is not designed to be difficult, and as long as you follow the instructions carefully and make sure the chip is fully inserted before locking it in place, you will be fine. However, there are some subtle differences in the process depending on your processor manufacturer, and processors are delicate, so be careful.

1. Locate the square socket for the processor. If the motherboard is new, it will have a plastic cover over it. Unplug the metal retaining lever and lift it up to release the plastic cover, then remove it.
2. To install the processor, you need to align it correctly. Most Intel processors have notches on the sides that allow you to place the processor in one orientation. On newer Intel processors you will also have a small golden triangle in one corner to help you with alignment. The same is true for all modern AMD processors.

Grasp the processor by the sides, being careful not to touch the underside, and align it properly using any aids provided. Then gently place it in the processor socket. Check again that it is in the correct position by moving the processor slightly from side to side. If it is in the correct place, it will move slightly. If it is not in the correct orientation, it will slide out of place. In that case, remove the processor and check the alignment before reinstalling it.

1. Once you are satisfied that the processor is installed correctly, firmly but gently lower the retaining arm until the processor is locked in place. This may require some pressure, but it should not be difficult. If you have any doubts, double-check that the processor was positioned correctly before locking it in place.

How to install RAM

System memory, or RAM, does not require the application of any kind of thermal paste and is one of the easiest components to install. The only caution is to choose the right slots, since most motherboards have four, and the best ones to use vary from motherboard to motherboard, so check the manual to find out which slots are best for installing your new RAM.

Before you begin, make sure your motherboard is well supported across its entire surface, as it is possible to put too much pressure on the motherboard when installing RAM if you push too hard. This eventuality is unlikely, but as with all the steps in this guide, be careful and, if in doubt, check everything before proceeding.

1. Once you have identified the slots in which to install the RAM, lower the plastic tabs on either side of the slot. Then, to confirm that your RAM module is oriented correctly, make sure the notch in the RAM module’s metal connectors lines up with the notch in the slot.

Place the module in the slot in an upright position. Press firmly until the RAM module clicks into place and the plastic tabs close and lock the module ends together.

1. Repeat the same process for each module until all your RAM is installed.

How to install the motherboard

The motherboard is the bulkiest component in your system, but because it serves as the base for everything else inside the case, installing it correctly is critical.

1. If your motherboard does not have a built-in backplate, take it out of the box-it looks like a small cutout of all the different ports on the motherboard-and install it on the back of your case, orienting it properly and pushing it into place. Check that it lines up properly with your motherboard’s outputs before you insert it if you’re not sure which direction it goes.
2. To install the motherboard, you must screw it onto the insulating spacers that prevent your components from shorting. Some cases already have them preinstalled, while others require you to install them yourself. They are easy to recognize because they have an unusual appearance-they are essentially screws that have another screw hole at the top instead of the classic screwdriver slot. They are usually gold or black in color.

If necessary, screw motherboard standoffs into the correct holes based on the size and layout of your motherboard. You can take a look at your motherboard to figure it out or install them where the manual suggests.

1. Place your motherboard in the case and push and move until it fits into the I/O panel and all of its screw holes line up with the standoffs underneath.

To secure the motherboard to the case, screw in the screws. First, position the screws and give them a couple of preliminary turns. Then proceed in a star pattern, tightening each screw a little at a time. Do not over-tighten; you may damage the board. Just enough torque is enough to hold the board in place without it moving.

1. Once the motherboard is firmly seated in the case, there are a few necessary connections to be made.

The main power connector on the motherboard is a two-row wide cable that fits neatly into a similar connector on the board itself. This 20-28 pin connector powers both the motherboard and the processor. However, some boards have one or two additional 4- or 8-pin connectors for the processor, usually located in the top corner.

It connects the case’s button and indicator connectors to the motherboard. A double row of pins, the location of which will be indicated in the manual, handles the reset and power buttons and the activity LEDs for power and storage. These can be particularly difficult to handle, but you must at least plug in the power button in order to turn on your PC.

The USB and audio connectors on the front panel will have their own location. These connectors are about 8 by 2 pins and are enclosed in a larger plastic housing. This connector has a notch on one side that should clearly indicate the direction in which it should be inserted.

How to install the processor heatsink

Installing a processor heatsink varies depending on the heatsink you are using, so for specific instructions consult the manufacturer’s manual or service site. Here are some simple steps that apply to most heatsinks.

1. Every heatsink needs thermal paste. You don’t necessarily have to use the best thermal paste, but be sure to use some. It usually looks like a silver paste and comes pre-applied to the heatsink or in a small syringe.

If you have to reapply thermal paste, be sure to remove the original one with a lint-free cloth and a little isopropyl alcohol.

When your processor is ready, apply a pea-sized amount to the center of the processor.

1. If your processor heatsink requires it, remove the other side panel of the case and attach the custom stand design. You may need to remove the standard stand from the motherboard first.
2. Place the heatsink on top of the processor and press down gently. Align any mounting brackets or bolts with the heatsink mounting holes on the motherboard.

Install the screws/fixing brackets to secure the heatsink firmly in place. If you have to tighten several screws, be sure to make only a couple of turns at a time in a crisscross pattern so you don’t put too much pressure on one part of the processor. Make sure they are tightened enough to keep the processor from moving, but don’t overtighten them.

1. If your heatsink has a separate fan, install it now and connect its 3- or 4-pin connector to the processor fan port on the motherboard. It will be located near the processor heatsink. If you have more than one, either connect them to other motherboard headers or use a splitter to power both from the processor fan port.

If you are installing an AIO liquid heatsink, mount the radiator in an appropriate place in the case (front or rear vents are common) and connect the fan connector to the correct port. You may also need to connect the pump connector, for which some motherboards have specific ports.

How to install the graphics card

Not all systems need a dedicated graphics card (discrete GPU), but if you are building a gaming PC, it is a necessity.

Intel Processors Intel processors mainly have integrated graphics, so if you’re not gaming, you don’t need a separate graphics card. Be careful, however, of processors with an “F” at the end-they do not include integrated graphics.

1. Modern graphics cards use a PCI-Express (PCIe) x16 slot. This is a long, thin connector located on the back of the motherboard, below the processor. For the vast majority of motherboards, you will have to use the top PCIe x16 slot.

To insert the card into that slot, you will have to remove one, two or in some cases three rectangular plates from the back of the case. They are one of many thin metal brackets lined along the back of the case to keep it sealed. Do this by removing the screw(s) that attach the plate(s) to the case. Once removed, the plate should slide (or fall) out freely.

Keep the screw aside; you will need it in a moment.

1. Take your graphics card and, making sure the ports line up with the back of the case and the PCI-Express connector is facing down, gently insert it into the motherboard slot. You should hear a click when the motherboard locks it in place, but that doesn’t always happen on every motherboard.

You don’t need too much force, so if you encounter a lot of resistance, take another look at the plate and PCIe slot to make sure both are clear and the motherboard is properly aligned. Also note if there is a locking pin like for your memory slots, as some motherboards use it as a safety measure.

1. Use the screws removed from the metal brackets to secure the back of the board. Again, they don’t have to be extremely tight-just enough to hold the card firmly in place.
2. Most graphics cards need more power than the PCIe slot can provide. If your card requires additional power, you will see one, two or even three PCIe power connectors on the side of the card facing away from the motherboard or, in some cases, on top of the card. This may be a traditional 6- or 8-pin PCIe connector or a new 12- or 16-pin mini design for new Nvidia GPUs.

Find the appropriate connector on your power supply, sometimes labeled VGA, and plug it in. The connector design prevents incorrect installation, so if the connection is not easy, check the alignment again to make sure it is correct. If your power supply does not have the required native connectors, you may have to use an adapter, which should be included with your graphics card.

How to install expansion cards

Graphics cards are not the only components that use PCIe slots. Other expansion cards include wireless networking, audio, video capture, and even storage. Their installation is no different from adding a discrete GPU.

There are 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 connectivity and the connector size on your board will make it obvious which slot is appropriate. If in doubt, consult your expansion card manual.

1. Remove the metal bracket on the back of the case corresponding to the PCIe or other slot that will house your new card. Keep the screw handy so you can use it to secure your new card.
2. Align the row of contacts on the card with the slot and press down firmly. If the board requires additional power from SATA or 4-pin Molex connectors, find the right cables and connect them to the board.
3. Secure the card in place by screwing it to the back of the case.

How to install hard drives and SSDs

There are three different sizes of storage drives you might encounter, and they mount and connect differently. In general, hard disk drives (HDDs) are the larger 3.5-inch size, while newer solid state drives (SSDs) adopt the smaller 2.5-inch format. There is also the even smaller M.2 and PCI-Express formats, which tend to be thin sticks with exposed chips a few inches long.

1. To install a hard drive, find 3.5-inch mounting points in your case. These may be complete hard drive cages with multiple mounting points, or it may just be a single drive space with screw holes directly in the case. If in doubt, consult the manual.

Insert your disk into the appropriate location and secure or lock it in place using the case’s mounting system. Once in place, connect the SATA data cable to the drive and motherboard, and the SATA power connector to the drive.

1. To install a SATA SSD, repeat the same steps as for the larger hard drive, changing only the mounting point to an appropriate 2.5-inch cage or slot-sometimes located behind the motherboard tray. Make sure it is securely fastened in place and connect both the power and SATA data cables.
2. To install an M.2 NVMe SSD, locate the appropriate slot on your motherboard. It will be labeled, but it is quite small, so check the manual if you are unsure.

Remove the retaining screw and insert the drive at a 45-degree angle. Gently but firmly press down on the drive until it snaps into place, then replace the retaining screw.

1. To install a PCIe SSD, choose an appropriate PCIe slot on your motherboard. The x16 slots will offer the most bandwidth, but may not be necessary for the bandwidth of your particular drive. Consult your drive manual to confirm which one is best for your motherboard.

Tilt the drive with the gold contacts facing down, then push gently until it snaps into place in the PCIe slot. It shouldn’t take much force, so if it sticks, check the alignment.

Connect any additional power cables you need.

Turn the PC on.

1. Turn on the power supply and press the power button on the front panel. If everything is okay, it should display the post screen or the manufacturer’s logo on the monitor, then go to the Windows installation or login screen. If it doesn’t, however, don’t worry. It is not uncommon for PCs to have to reboot a couple of times when they first start up, and some may even take a few minutes to boot up the first time while they configure memory and other components.

If you encounter error messages or beeps, consult your motherboard manual to decode them and figure out what you need to fix.

If it does not turn on at all, turn off the power supply and recheck all connections. Also make sure the wall outlet is turned on. For further assistance, see our PC troubleshooting guide.

1. Once the system has booted up, you will need to install Windows. If you don’t know how to do this, here is a brief guide on how to download and install Windows.
2. Once you get to Windows, you will need to install the drivers. Windows 10 and 11 already support modern chipsets and will automatically download and install the remaining drivers in most cases. Check the “Update and Security” menu in the Settings panel for more information on this process.

If this doesn’t work, the chipset driver for your motherboard will handle most of the connectivity and built-in features, although this varies greatly by motherboard and component manufacturers. You can download the latest version from your motherboard manufacturer’s website.

If you have a discrete graphics card, you will need to download graphics drivers from the AMD page for Radeon drivers or the Nvidia page for GeForce drivers.

Don’t forget about peripherals

It’s easy to get caught up in the excitement of building a gaming PC and forget that you need peripherals to make it work. If you still need a keyboard, monitor, and mouse to complete your setup, we can point you in the right direction:

• Best Keyboards
• Best computer mice
• Best computer monitors

With a little luck and a lot of attention to detail, you should have a fully operational system. Keep an eye on your system temperatures for a few days to make sure all the heatsinks are working properly, and if an error message appears, deal with it accordingly. After a few weeks, you will become familiar with your machine and more confident about what you can get it to do. If something breaks or needs an upgrade, you’ll be fully equipped to deal with it.

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