What you need before you start building
Building a PC means assembling a motherboard, CPU, RAM, storage, power supply, and case into a working computer. You will need the actual parts, a workspace, and a few tools — most of which you probably have at home. The process takes two to four hours for a first-time builder, and the main risk is static electricity damaging components, not physical damage from assembly itself.
Gather these items before you open any boxes: a Phillips head screwdriver (magnetic tip helps), an anti-static wrist strap or mat (or simply touch a metal part of the case frequently to discharge static), your motherboard manual, and a clean, flat surface with good lighting. You do not need special tools or a workshop. A kitchen table works fine as long as you keep liquids away and avoid carpeted areas if possible — carpet generates static more easily than hard floors.
Read your motherboard manual before you start. Every motherboard is slightly different, and the manual shows you exactly where each component plugs in, which slots are which speed, and how the power connectors line up. Manufacturers include these manuals in the box or post them free on their website — search "[your motherboard model] manual PDF" to find it.
Key Takeaways
- Static electricity is the main risk to components, so wear an anti-static wrist strap or touch the metal case frame regularly to stay grounded.
- Install the CPU, RAM, and M.2 storage onto the motherboard while it is outside the case, because access is easier and mistakes are less likely.
- Mount the motherboard into the case first, then connect the power supply, then plug in the front panel connectors and any additional fans or RGB headers.
- The power supply fan should face downward if your case has ventilation holes in the bottom; otherwise it faces upward into the case.
- Do not force any component into a slot — if it does not slide in smoothly, check the alignment and try again rather than pushing harder.
Installing the CPU and RAM before the case
Start with the motherboard on a flat surface outside the case. Install the CPU first: open the retention bracket on the socket (usually a lever on the side), align the CPU with the socket so the notches match, and lower it gently into place. The CPU should sit flat without any pressure — if you have to push down hard, the alignment is wrong. Close the retention bracket and secure the cooler according to its instructions, which vary widely between air coolers and liquid coolers.
Install RAM next. Open both clips at the ends of the RAM slot, align the notch in the RAM stick with the key in the slot, and press down firmly until both clips snap closed on their own. You should hear a click. RAM requires real pressure — this is one of the few places where "firm" is correct — but the stick should not bend or flex. If it does not click after hard pressure, remove it and check the alignment again.
Install your M.2 storage drive if you have one: remove the small screw from the M.2 slot, insert the drive at a 30-degree angle, then press down and secure it with the screw. Some motherboards have a heatspreader over the M.2 slot — remove it first, install the drive, then replace the heatspreader. Check your manual for the exact location, because some boards have multiple M.2 slots and they may run at different speeds.
Mounting the motherboard into the case
Place the case on its side so you can see inside clearly. Locate the I/O shield — a metal plate that came with your motherboard or is already in the case — and make sure it is installed in the rectangular opening at the rear of the case. The shield has cutouts for USB ports, audio jacks, and other connectors, and it must be seated fully or the motherboard will not fit flush.
Install the brass standoffs into the case at the screw holes that match your motherboard. Standoffs are small brass cylinders that screw into the case and prevent the motherboard from touching the metal case directly, which would short it out. Most cases come with some standoffs pre-installed; check which holes your motherboard uses and add or remove standoffs to match. Do not install a standoff where there is no hole on the motherboard — an extra standoff touching the board will cause a short.
Carefully lower the motherboard into the case, aligning the I/O ports with the shield cutouts and the screw holes with the standoffs. Once aligned, screw the motherboard down with the Phillips head screwdriver. Tighten each screw a little at a time in a cross pattern (like tightening a car wheel) rather than fully tightening one screw, then moving to the next. This keeps the board flat and prevents warping.
Installing the power supply and connecting power
Slide the power supply into its bay at the bottom or rear of the case, depending on your case design. The fan on the power supply should face downward if your case has ventilation holes in the bottom; if not, face it upward into the case. Secure it with four screws on the outside of the case. The power supply connector (a large rectangular plug) should face toward the motherboard so the cable can reach without stretching.
Connect the 24-pin ATX power connector to the motherboard — this is the large rectangular plug that powers the entire board. Find the 24-pin header on the motherboard (your manual shows its location), align the connector, and press firmly until it clicks. Connect the 8-pin or 4-pin CPU power connector near the CPU socket next. Some high-end boards have both an 8-pin and a 4-pin; install both if present.
Connect SATA power to any 2.5-inch or 3.5-inch storage drives you have. SATA power is a flat connector with three rows of pins. Connect SATA data cables from the motherboard to those same drives — SATA data is a smaller, L-shaped connector. If you are using only an M.2 drive, you do not need SATA power or data cables. Connect PCIe power (6-pin or 8-pin connectors) to your graphics card if you have one, following the card's manual for the exact location.
Connecting front panel headers and fans
The front panel connectors are small pins that connect the power button, reset button, and LED lights on the case front to the motherboard. Your motherboard manual shows a diagram of the front panel header — it is usually a small cluster of pins near the bottom edge of the board. The connectors are tiny and easy to misplace, so work slowly and check the manual for polarity (which direction the connector faces). Most cases label the wires: PWR_SW for power, RST_SW for reset, PWR_LED for the power light, and HDD_LED for the activity light.
Connect case fans to the motherboard fan headers if your case has them. Most cases come with one or two fans already installed. Connect them to headers labeled FAN1, FAN2, or similar on the motherboard. Some fans connect to a separate fan hub or controller instead — check your case manual. If your case has RGB lighting, connect that to an RGB header on the motherboard or to a separate RGB controller, depending on your setup.
Connect the front panel USB and audio connectors if your case has them. These are larger connectors than the power button pins and are harder to misalign. The USB 3.0 header is a large rectangular connector; the USB-C header (if present) is smaller. Audio is a single 3.5mm jack or a pin header. Your motherboard manual shows where each one plugs in. These are optional — the PC will work without them — but they make the front ports functional.
Installing storage drives and the graphics card
Install any 2.5-inch or 3.5-inch drives into their bays. Most cases have a drive cage or bracket that holds drives in place. Slide the drive in, align the screw holes, and secure it with four screws. Connect the SATA data and power cables you ran earlier. If your case does not have a drive cage, some cases include a 2.5-inch bracket that mounts to the side of the case — check your case manual for the location.
Install your graphics card if you have one. Remove the slot covers at the rear of the case that correspond to the PCIe slot you are using (usually the top PCIe x16 slot). Open the retention clip at the end of the slot, align the card with the slot, and press down firmly until the clip snaps closed. The card should sit flush with the rear of the case. Secure the card's bracket to the case with screws. Connect any PCIe power cables you ran earlier.
Install any additional case fans you want to add. Most cases have fan mounts on the front, rear, and top. Align the fan with the mounting holes, secure it with four screws, and connect it to a fan header on the motherboard or to a fan hub. Make sure the fan is facing the right direction — intake fans pull air into the case, exhaust fans push air out. A common setup is intake fans on the front and bottom, exhaust fans on the rear and top.
Testing and first startup
Before you close the case, do a visual check: make sure all power connectors are fully seated, no cables are pinched between components, the motherboard is fully screwed down, and the CPU cooler is secure. Power on the PC using the power supply switch on the back, then press the case power button. The fans should spin, lights should turn on, and you should hear a beep from the speaker (if one is installed). If nothing happens, turn it off immediately and check that the 24-pin and CPU power connectors are fully clicked in.
If the PC starts, let it run for a minute to make sure nothing overheats or smells wrong. Then shut it down, close the case, and install your operating system. You will need a USB drive with Windows, Linux, or macOS on it, depending on what you want to run. Most motherboards come with drivers on a CD or available for download from the manufacturer's website — install those after the operating system is running so all components work at full speed.
If the PC does not start or starts but immediately shuts down, the most common causes are a loose power connector, RAM not fully seated, or the CPU cooler not making proper contact. Power off, unplug the power supply, wait 30 seconds, then reseat the RAM and check all power connectors before trying again.
Frequently Asked Questions
Do I need thermal paste if my CPU cooler comes with it pre-applied?
No. Most modern coolers come with thermal paste already on the base plate. If yours does not, or if you are reusing an old cooler, apply a small pea-sized amount to the center of the CPU before installing the cooler. Too much paste is worse than too little — it reduces cooling performance.
What if my motherboard does not have an M.2 slot?
Use a 2.5-inch SSD instead, which connects via SATA data and power cables just like a traditional hard drive. Older motherboards may only have SATA slots, and 2.5-inch SSDs work perfectly fine in those systems. You will not notice a speed difference in everyday use compared to M.2 drives.
Can I install components with the power supply turned on?
No. Always turn off the power supply switch on the back of the case and unplug the power cable before touching any internal components. Even with the PC off, the power supply can deliver a shock if you touch certain parts. Unplugging removes that risk entirely.
How do I know if my case has enough space for my graphics card?
Check your graphics card's length in millimeters (usually listed on the box or manufacturer's website) and compare it to your case's maximum GPU length (listed in the case manual or specifications). Also check the height — some tall CPU coolers can block the top PCIe slot. If your card does not fit, you will need a larger case or a shorter card.
What should I do if a component does not fit or feels stuck?
Stop and do not force it. Remove the component, check the alignment against your motherboard manual, and try again. Forcing components can bend pins, crack circuit boards, or break plastic retention clips. If something still will not fit after checking alignment twice, verify you have the right part for your motherboard before trying a third time.