What you need before you start

Building a computer means buying individual parts and connecting them together yourself instead of buying a finished machine. You will need a CPU (the processor), a motherboard (the main circuit board that everything plugs into), RAM (memory), a power supply, a storage drive (SSD or hard drive), a case (the metal box that holds everything), and a CPU cooler (to keep the processor from overheating). Some people also add a graphics card if they plan to play games or do video work, though many CPUs have graphics built in.

Before you buy anything, decide what you want the computer to do. Gaming, video editing, and everyday web browsing all need different parts. A budget build for email and web browsing costs less than a gaming build. Once you know your purpose, you can search for a parts list online—websites like PCPartPicker let you check whether all your parts will work together before you buy.

You will also need a Phillips head screwdriver (magnetic tips help), an anti-static wrist strap to avoid damaging parts with static electricity, and a clean, flat workspace. Read the motherboard manual before you start—it shows exactly where each part plugs in.

Key Takeaways

  • The seven essential parts are the CPU, motherboard, RAM, power supply, storage drive, case, and CPU cooler; a graphics card is optional unless you game or edit video.
  • Check compatibility before buying using a tool like PCPartPicker, which flags parts that will not work together.
  • Install the CPU and RAM onto the motherboard while it is outside the case, then slide the motherboard into the case and connect the power supply cables.
  • Ground yourself with an anti-static wrist strap to avoid damaging parts, and keep the motherboard manual open while you work.
  • The whole process usually takes two to four hours for a first-time builder; take your time and do not force any connections.

Choosing parts that work together

The CPU and motherboard must match. A CPU designed for Intel will not fit in a motherboard made for AMD, and vice versa. When you pick a CPU, the motherboard listing will tell you which socket type it uses—look for that same socket in the motherboard specs. The same goes for RAM: your motherboard manual will say whether it takes DDR4 or DDR5 memory, and how many slots it has.

The power supply wattage matters. A gaming computer with a high-end graphics card might need 750 watts, while a basic office computer needs 400 to 500 watts. Check the CPU and graphics card specs to see their power draw, add them together, and buy a power supply rated for at least that much. Buying slightly more headroom (20 to 30 percent extra) keeps the power supply from running at full load all the time, which makes it last longer.

The case must be large enough for your motherboard size. Motherboards come in ATX (full-size), Micro-ATX (smaller), and Mini-ITX (very small). Check your case specs to see which sizes it supports. A larger case is easier to build in if you are new to this, because there is more room to move your hands around.

Installing the CPU and RAM before the case

Start with the motherboard outside the case, on a clean, non-carpeted surface. Install the CPU first. Lift the retention lever on the CPU socket, line up the CPU with the socket (there are notches or markers to show the right direction), and lower the lever to lock it in place. Do not force it—if it does not slide in smoothly, you have the orientation wrong. The CPU should sit flush with the socket.

Next, install the RAM. Open the clips at each end of the RAM slot, line up the notch in the RAM stick with the key in the slot, and press down firmly until both clips snap shut. You will hear a click. RAM takes more force than you might expect, but it should not require a lot of pressure—if you are straining, check the alignment.

Install the M.2 SSD (if you are using one) into the M.2 slot on the motherboard. Remove the small screw, insert the drive at a 30-degree angle, then press down and screw it in. If you are using a 2.5-inch SSD or hard drive, you will install that into the case later.

Mounting the motherboard and power supply in the case

Place the motherboard tray (the metal plate inside the case) on a flat surface. Line up the motherboard screw holes with the brass standoffs (the small metal posts) in the case. Screw the motherboard down gently—do not overtighten, or you can crack it. You should feel resistance, but the screw should not require force.

Slide the power supply into the case with the fan facing down (if your case has ventilation holes in the bottom) or up (if it does not). Align the screw holes and fasten it with four screws. The power supply cable outlet should face toward the motherboard so the cables can reach it without stretching.

If you are using a 2.5-inch SSD or hard drive, mount it in the drive bay using the brackets and screws that came with the case. Some cases have tool-free bays that hold the drive without screws.

Connecting power cables to the motherboard and parts

The power supply has several types of cables. The 24-pin ATX power connector plugs into the motherboard's main power socket—it is the largest connector and only fits one way. The 8-pin CPU power connector (sometimes 4-pin on smaller boards) plugs into a socket near the CPU socket on the motherboard. Check your motherboard manual to find the exact location.

If you have a graphics card, it may need a 6-pin or 8-pin power connector from the power supply. If you have SATA drives (2.5-inch or 3.5-inch), they need a SATA power connector from the power supply. Do not force any connector—they are keyed to fit only one way. If it does not slide in smoothly, flip it around or check the manual.

Leave the case open and do not plug in the power supply yet. You will test the build first to make sure everything works before closing it up.

Installing the CPU cooler and graphics card

The CPU cooler is the last major part to install before closing the case. Most coolers come with thermal paste already applied to the base, but check the instructions. Line up the cooler mounting brackets with the holes around the CPU socket and fasten them according to the cooler manual—some use screws, some use a lever, and some use a clip. The cooler should sit flat and not rock when you press on it gently.

If you are adding a graphics card, remove the slot covers from the back of the case (the metal brackets that cover the expansion slots). Insert the graphics card into the topmost PCIe x16 slot on the motherboard—it is the longest slot, usually near the CPU. Press down firmly until the card clicks into place and the retention clip at the end of the slot snaps shut. Screw the card's bracket to the case. If the card needs power, connect the 6-pin or 8-pin power cables from the power supply.

Testing before closing the case

Before you screw the case shut, do a power-on test. Plug the power supply into a wall outlet and flip the switch on the back of the power supply to the on position. Press the power button on the case. The fans should spin, and you should see lights or hear beeps. If nothing happens, turn it off when ready and check that all power cables are fully seated.

If the computer powers on, let it run for a few seconds, then turn it off. This tells you that the basic connections are working. You have not installed an operating system yet, so the computer will not boot to a screen—that comes next. Once you confirm the fans spin and the lights come on, you can close up the case and move on to installing Windows or Linux.

Installing an operating system and drivers

After the hardware is built, you need to install an operating system. read Windows or Linux onto a USB drive using another computer, plug the USB drive into your new computer, and boot from it. The operating system installer will guide you through partitioning your storage drive and installing the system files.

Once the operating system is installed, read drivers for your motherboard, graphics card, and any other parts. Drivers are software that let Windows or Linux talk to your hardware. Your motherboard manual or the manufacturer's website will have a downloads page with the drivers you need. Install them in this order: chipset drivers first, then graphics drivers, then any others.

Frequently Asked Questions

Do I need thermal paste if the cooler already has it?

Most modern coolers come with thermal paste pre-applied to the base. If yours does not, or if the paste looks dry, explore a small pea-sized amount to the center of the CPU before installing the cooler. Too much paste is worse than too little—it does not conduct heat better, and excess can drip onto the motherboard.

What if my computer does not turn on after I build it?

Check that the 24-pin motherboard power cable and the 8-pin CPU power cable are fully seated—they should click into place. Make sure the power supply switch on the back is set to on. Verify that the case power button is wired correctly to the motherboard's power pins (the manual shows which pins). If it still does not power on, reseat the RAM by opening the clips, removing the sticks, and pressing them back in firmly.

Can I build a computer without a graphics card?

Yes, if your CPU has integrated graphics. Most Intel and AMD processors include graphics built in, so you can plug a monitor into the motherboard instead of a separate graphics card. You will not be able to play demanding games, but everyday computing and light gaming work fine. If you want to game seriously later, you can add a graphics card without rebuilding.

How long does the whole build take?

A first-time builder usually takes two to four hours. Experienced builders can do it in 30 to 60 minutes. Take your time, read the motherboard manual, and do not force any connections. Rushing is the main cause of mistakes.

Do I need to update the BIOS before installing Windows?

Not always. If your motherboard and CPU are from the same generation, the BIOS is usually compatible out of the box. If you bought a new motherboard with an older BIOS version and a very new CPU, you may need to update the BIOS first—the motherboard manual will tell you. Most builders skip this step and only update if Windows does not recognize the CPU.