What you need before you start
Building a PC means buying individual components — a motherboard, CPU, RAM, storage, power supply, case, and cooling — then physically connecting them together. You do not need special training or tools. Most connections are designed to fit only one way, and the parts themselves are tougher than they look. What you do need is a clean, flat workspace, a Phillips-head screwdriver, and about two to three hours of uninterrupted time.
Before you buy anything, decide what you want the PC to do. Gaming, video editing, and everyday browsing all point toward different component choices and price ranges. Once you know that, use a parts compatibility checker like PCPartPicker to make sure your motherboard, CPU, and RAM work together — these three must match. PCPartPicker also flags power supply wattage issues and case size problems before you order.
Ground yourself before touching components. Static electricity can damage parts. Touch a metal part of your case, wear an anti-static wrist strap, or work on a non-carpeted surface. Do not work on carpet if you can avoid it.
Key Takeaways
- The CPU, RAM, and motherboard must be compatible with each other before you buy — use PCPartPicker or your motherboard manual to verify.
- Install the CPU and RAM into the motherboard while it is outside the case, then place the motherboard into the case and screw it down.
- Connect the power supply to the motherboard, CPU, and storage drives using the cables that came with the power supply.
- The most common mistake is forgetting the CPU power cable (a separate 4-pin or 8-pin connector near the CPU socket), which will prevent the PC from starting.
- After assembly, plug in the power supply, flip the switch on the back, and press the power button — if nothing happens, check that the CPU power cable is fully seated.
Installing the CPU and RAM before the case
Start with the motherboard outside the case, placed on a non-static surface like the box it came in. Locate the CPU socket — it is a large square with a hinged metal lever on one side. Lift the lever all the way up. The CPU has a small notch or arrow on one corner; line that up with the matching notch on the socket, then gently place the CPU into the socket without forcing it. Lower the lever back down. The CPU should sit flush with no gaps.
RAM slots are long, thin sockets next to the CPU. Open the clips at both ends of each slot by pushing them outward. Line up the notch in the RAM stick with the key in the slot, then press down firmly on both ends until the clips snap closed. You should hear a click. RAM is fully seated when the clips hold it in place and no gold connectors are visible.
If you are using a CPU cooler (most CPUs come with one), install it now while the motherboard is flat and easy to work with. Follow the cooler's instructions — some screw down, some use clips, and some use thermal paste that you apply to the CPU first. The manual that came with your cooler is the source of truth here, not a general guide.
Preparing the case and installing the motherboard
Open your case by removing the side panels. Most cases have two panels held by thumbscrews or regular screws. Look for the I/O shield — a thin metal plate that came with your motherboard. It slides into the rectangular opening at the back of the case from the inside. Push it in until it clicks or sits flush.
Locate the motherboard standoffs — small brass posts screwed into the case that prevent the motherboard from touching the metal case directly. Your case should come with these already installed, but check that they line up with the screw holes on your motherboard. If standoffs are missing or misaligned, add or move them now.
Carefully lower the motherboard into the case, lining up the screw holes with the standoffs. The ports on the back of the motherboard should align with the I/O shield opening. Once aligned, screw the motherboard down using the screws that came with the case. Do not overtighten — snug is enough.
Connecting power to the motherboard and CPU
The power supply has a large 24-pin connector and a separate 4-pin or 8-pin connector. The 24-pin connector plugs into the motherboard's main power socket, usually located along the right edge. The 4-pin or 8-pin connector plugs into a socket near the CPU, usually in the top-left corner of the motherboard. Both connectors are keyed and only fit one way. Push them in until they click.
This CPU power cable is the most commonly forgotten step. If your PC does not start after assembly, this is the first thing to check. Make sure it is fully seated — you should not see any gold pins.
If your motherboard has a 24-pin power socket and your power supply has a 20-pin connector, they are still compatible. The 20-pin connector will slide into one end of the 24-pin socket. This is normal and safe.
Installing storage drives and connecting them to power
Solid-state drives (SSDs) are the most common choice now. M.2 SSDs are small and plug directly into a slot on the motherboard — no cables needed. Locate the M.2 slot (check your motherboard manual if you cannot find it), remove the small screw and standoff, insert the drive at a 30-degree angle, then press down and screw it in place.
If you are using a 2.5-inch SSD or a 3.5-inch hard drive, mount it in a drive bay inside the case using the screws that came with the case. Then connect a SATA power cable from the power supply to the drive, and a SATA data cable from the motherboard to the drive. SATA connectors are L-shaped and only fit one way.
M.2 drives do not need power cables. SATA drives need both a power cable and a data cable. Check your motherboard manual to see which SATA port to use — usually SATA0 or SATA1 is the first choice.
Installing the graphics card and other expansion cards
If you bought a dedicated graphics card, locate the PCIe slot on the motherboard — it is a long horizontal slot, usually below the CPU. Remove the metal bracket at the back of the case that covers the slot opening. Push the retention clip at the end of the PCIe slot toward the back of the case to open it. Line up the card with the slot and press down firmly until the clip snaps closed. Screw the bracket on the back of the card to the case.
Graphics cards often need extra power. Check if your card has a 6-pin or 8-pin power connector on the top edge. If it does, plug in the matching cable from the power supply. If you do not have the right connector, your power supply does not have enough capacity for that card.
Most CPUs have built-in graphics, so a dedicated card is optional. If you are not gaming or doing graphics-heavy work, you do not need one.
Final connections and powering on
Before you close the case, double-check three things: the CPU power cable (4-pin or 8-pin near the CPU), the main motherboard power cable (24-pin), and the RAM (both clips closed, no gold visible). These three account for most "it will not start" problems.
Connect your monitor to the graphics card if you have one, or to the motherboard if you are using built-in graphics. Plug the power supply cable into a wall outlet. Flip the power switch on the back of the power supply to the on position. Press the power button on the front of the case. The fans should spin and lights should come on. If nothing happens, turn off the power supply, wait 10 seconds, and check that the CPU power cable is fully seated.
Once the PC powers on, you can close the case panels. You will need to install an operating system (Windows, Linux, or macOS depending on your hardware) using a USB drive or installation media before you can use the PC for anything.
Frequently Asked Questions
What if my PC powers on but immediately shuts off?
This usually means the CPU cooler is not making proper contact with the CPU, or the CPU power cable is loose. Power off, wait 10 seconds, then reseat the CPU cooler by removing it and reapplying thermal paste if needed. Also check that the 4-pin or 8-pin CPU power cable is fully clicked in. If the cooler is the stock cooler that came with the CPU, follow its manual exactly.
Do I need thermal paste if my cooler comes with it pre-applied?
No. Most stock coolers come with thermal paste already on the base. If you see a clear plastic film on the cooler's base, peel it off before installing. Do not add more paste unless the cooler's manual tells you to.
Can I touch the components while building, or will static destroy them?
You can touch components, but ground yourself first by touching a metal part of the case or wearing an anti-static wrist strap. Avoid working on carpet. Static damage is possible but rare if you take basic precautions. Do not be paralyzed by fear — millions of people build PCs in normal conditions without problems.
What if I put the RAM in the wrong slot?
RAM will only fit into the correct slot because of the notch. If it does not slide in easily, you are trying the wrong slot or the wrong direction. Do not force it. Check your motherboard manual to see which slots to use — usually slots 2 and 4 if you have two sticks, or slot 2 if you have one.
Do I need to install drivers after assembly?
Your motherboard will boot with basic drivers built into Windows. For best performance, download chipset drivers from your motherboard manufacturer's website and install them. Graphics card drivers should also be updated from the GPU manufacturer's website (NVIDIA, AMD, or Intel). These are optional for the PC to work, but recommended.