How to build your own PC

Assembling your own PC from scratch is a very rewarding experience. It may take a lot of time to choose compatible hardware components, put everything together and then install an operating system but you will learn a lot about hardware and software in the process and this knowledge will prove invaluable when it comes to troubleshooting, upgrades and maintenance later on. Before you begin assembling your new computer, ensure that you have all of the following items and that they are all compatible with each other:

• Case and power supply (PSU)
• Motherboard
• Processor (CPU)
• Memory
• Processor heat sink, fan and thermal paste (usually comes with the CPU)
• Graphics card
• Hard disk
• Optical drive
• SATA hard drive and optical drive cables (usually comes with motherboard)
• Any additional extras such as sound card, TV tuner card and card reader.
• Peripherals including monitor, keyboard and mouse

Once you have all of these components, you are ready to start unpacking and building your new dream computer!

1 – Installing the Power Supply

How to build your own PC

Put the case on its side on a hard, stable surface and remove the side cover. If your case doesn’t already come with a PSU installed, you will need to install one yourself. Place the PSU in the bay at the top-back of the case. You will need to screw it into place with three or four screws, depending on how many holes are provided.

2 – Installing the Motherboard

How to build your own PC

Line up the screw holes in the motherboard with those provided on the motherboard tray in the side of the case. You may need to attach some copper spacers to the motherboard tray. These should be provided with the set of fittings provided with the case. Again, line up the motherboard with the copper spacers on the tray and connect screws to all of the available holes.

3 – Installing the Processor

How to build your own PC

Lift up the bar beside the processor socket. Provided it is correctly aligned with the socket, the processor should simply fall into place. Do not attempt to force it! With the processor in place, pull down the bar to lock it. Place the cooling unit on top of the processor, ensuring that there is a pad of thermal grease on the bottom of the heat sink. This is normally already provided. If not, you will need to apply some yourself to ensure proper heat dissipation. With the heat sink in place, place the clips on either side of it around the notches each side of the processor socket. Pull down the retention bar to lock it firmly in place.

4 – Installing the Memory

How to build your own PC

Locate the long, thin memory sockets on the motherboard and pull back the clips at each end of the sockets you need. Put the memory sticks in place. If they are the right way round, they should fit in easily. Do not force them in! Put the clips and the ends of the sockets forward again to lock the memory modules in place.

5 – Install the Graphics Card and Any Other PCI Cards


Remove the back plates in the back of the case behind any expansion slots that you need to use. The graphics card slot will be located closest to the top of the case. Insert the graphics card into this slot and insert any other add-in cards such as a TV card or sound card into available slots. Fortunately, it is not possible to install anything into an incorrect slot. Be sure to attach a screw to the L-shaped bracket on the back of the graphics card and any other add-in cards to the back of the case.

6 – Install the Drives

How to build your own PC

Install the hard drive into an available 3.5″ bay in the front of the case and connect it with four screws unless your case has a special screw-free design. For the optical drive, remove a front panel from the front of the case and install the drive in the same manner but in a 5.25″ drive bay. If you have a card reader, install this in an available external 3.5″ drive bay after removing the cover on the front of the case.

7 – Connecting the Cables

How to build your own PC

First connect the 24-pin and 4-pin power cables from the PSU to the motherboard. Connect the small cable from the processor fan to the socket labelled “CPU_FAN” or something similar on the motherboard. Connect two 6-pin power cables from the power supply to the sockets on the side of the graphics card. If you have a low-end graphics card, these slots may not be available in which case you don’t need to worry about them. Finally, connect the SATA power cables from the PSU to the hard drive and the optical drive. All of these connections are fairly obvious and the plugs cannot be connected incorrectly.

Connect a SATA cable from available sockets on the motherboard to the hard drive and optical drive. The sockets on the motherboard will likely be labelled “SATA_1” and “SATA_2” or something similar. Most motherboards provide at least two of these. Connect the cable from the card reader (if you have one) to an available internal USB port on the motherboard. Again, it should be obvious where cable connects to.

Now you will need to connect the front panel connectors. These control things such as the power and reset switch and the power and hard drive LEDs as well as additional case functions. If you have any front USB ports, connect the larger set of cables from the front of the case to an available port on the motherboard. If you have front panel audio connections, connect these to the port labelled “HD_AUDIO” or something similar on the motherboard or to a dedicated sound card if you are using one.

Finally, locate the front panel connectors on the motherboard. This is typically a row of eight by two pins near the edge of the motherboard. There should be labelled pins for the power switch, reset switch, power LED and hard drive LED. Connect them as required. Don’t worry if you connect them to the wrong pins – all that will happen is that the specific function won’t work. Every motherboard’s front panel connector varies slightly so you may need to refer to your motherboard schematics.

Finishing Up

Now that everything has been assembled, you can connect the monitor, keyboard, mouse and speakers. Leave the cover off for now, just in case you need to change anything. Connect the power cable to your computer and turn it on. If you get a beeping noise when the computer turns on, this means that there is an error such as an incorrectly installed memory module or an incompatible processor. Check with the motherboard manufacturer to find out exactly what the beep code is referring to. If you installed everything correctly and your components are all compatible, however, your computer should start up and you can install the operating system.

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