Building your first PC: Step-by-step assembly process
By Ben, BPU Contributor
Updated on
Follow our detailed step-by-step guide to assembling your custom PC. From installing the CPU to connecting the power supply, we cover each step thoroughly.
This is part of a 10-page guide on How to build your first PC. If you haven’t seen the other parts yet, make sure to check out this link to explore the entire guide.
Step-by-Step Assembly Process
Now that you’ve gathered your tools, set up your workspace, and prepared your components, it’s time to start assembling your PC. This section will guide you through the process step by step, ensuring that each component is installed correctly and that your build is functional and efficient.
A. Installing the CPU
1. Open the CPU Socket on the Motherboard:
Locate the CPU socket on the motherboard. It will usually be covered by a small protective plastic cover.
Lift the retention arm or bracket next to the socket to open it. This will allow you to insert the CPU.
2. Align the CPU with the Socket:
Take the CPU out of its packaging, being careful to hold it by the edges.
Align the notches or triangle on the corner of the CPU with the corresponding marks on the socket. This ensures the CPU is correctly oriented.
Carefully lower the CPU into the socket. It should fit snugly without any force. If it doesn’t, double-check the alignment.
3. Secure the CPU:
Once the CPU is seated properly, lower the retention arm or bracket to secure it in place.
If the socket had a protective cover, it may pop off when you secure the CPU. You can discard this cover, as it’s no longer needed.
B. Installing the CPU Cooler
1. Apply Thermal Paste (if not pre-applied):
If your CPU cooler doesn’t have thermal paste pre-applied, you’ll need to apply it manually.
Place a small pea-sized dot of thermal paste in the center of the CPU. This will spread evenly when the cooler is installed, creating a thin layer that improves heat transfer.
2. Mount the CPU Cooler:
Air Cooler: Position the cooler over the CPU, aligning it with the mounting bracket or screws on the motherboard. Carefully lower it onto the CPU, ensuring even contact. Secure the cooler by tightening the screws or clips in a diagonal pattern to ensure even pressure.
Liquid Cooler: If you’re using a liquid cooler, first attach the radiator and fans to the case (usually at the top or front). Then, mount the cooling block onto the CPU, securing it with the provided hardware. Ensure all screws are tightened evenly.
3. Connect the Cooler’s Power Cable:
Plug the cooler’s fan or pump cable into the appropriate header on the motherboard (usually labeled CPU_FAN or PUMP_FAN). This powers the cooler and allows the motherboard to control the fan speed based on CPU temperature.
C. Installing RAM
1. Open the RAM Slots:
Locate the RAM slots on your motherboard. There are usually two or four slots, depending on your motherboard’s form factor.
Push down on the tabs at either end of the RAM slots to open them. These will click into place when the RAM is correctly installed.
2. Align and Insert the RAM Sticks:
Take your RAM sticks and align the notch on the bottom of each stick with the corresponding notch in the slot. This ensures the RAM is oriented correctly.
Insert the RAM stick into the slot and press down firmly on both ends until the tabs click back into place, securing the stick. If the RAM doesn’t click in easily, check the alignment and try again.
3. Install RAM in the Correct Configuration:
If you have multiple sticks, consult your motherboard manual to determine the correct slots for dual-channel or quad-channel configurations. This maximizes memory performance.
D. Mounting the Motherboard
1. Install the I/O Shield:
Before placing the motherboard in the case, install the I/O shield. This metal plate covers the rear I/O ports (USB, audio, etc.) and snaps into the back of the case. Ensure it’s oriented correctly, with the cutouts matching the motherboard’s ports.
2. Align the Motherboard with Standoffs:
Place the motherboard into the case, aligning it with the standoffs (small, raised screw mounts) pre-installed in the case. The motherboard should line up with the I/O shield at the rear.
If necessary, adjust the standoffs so they match the mounting holes in your motherboard.
3. Secure the Motherboard:
Using the screws provided with your case, secure the motherboard to the standoffs. Tighten the screws gently to avoid over-tightening, which could damage the motherboard.
E. Installing the Power Supply Unit (PSU)
1. Position the PSU:
Depending on your case, the PSU will usually be installed at the bottom or top. If your case has a bottom mount, the PSU should be positioned with the fan facing downwards (assuming your case has ventilation at the bottom) to draw in cool air from outside the case.
Slide the PSU into place, aligning it with the screw holes in the case.
2. Secure the PSU:
Use the screws provided with the PSU to secure it to the case. Ensure it’s firmly attached, as it will support the weight of all connected cables.
3. Connect the PSU Cables:
Route the necessary cables (24-pin ATX power for the motherboard, 8-pin CPU power, PCIe power for the GPU, SATA power for storage drives) to their respective components. Don’t connect them yet; just route them to keep things organized.
F. Installing Storage Drives
1. Mount SSDs or HDDs:
Depending on your case, you may have tool-less drive bays, brackets, or trays. For SSDs, consider mounting them in dedicated 2.5-inch slots or trays.
For HDDs, use the 3.5-inch drive bays. Slide the drive into the bay or tray and secure it with screws if necessary.
2. Connect the Storage Drives:
For SATA SSDs/HDDs: Connect one end of the SATA data cable to the drive and the other end to a SATA port on the motherboard. Then, connect a SATA power cable from the PSU to the drive.
For NVMe SSDs: Insert the NVMe SSD into the M.2 slot on the motherboard at a slight angle. Press it down and secure it with the provided screw.
G. Installing the GPU
1. Remove PCIe Slot Covers:
Identify the PCIe slot where the GPU will be installed, typically the first full-length slot on the motherboard.
Remove the corresponding slot covers from the case’s rear by unscrewing them. Keep these screws handy, as you’ll use them to secure the GPU.
2. Insert the GPU:
Align the GPU with the PCIe slot and gently insert it. Press down until the card clicks into place, securing it in the slot.
Once the GPU is seated, secure it to the case using the screws from the slot covers.
3. Connect PCIe Power Cables:
Connect the necessary PCIe power cables from the PSU to the GPU. Most mid-range to high-end GPUs require additional power beyond what the PCIe slot provides.
H. Cable Management
1. Organize Cables:
Begin routing your cables neatly through the case’s cable management holes and channels. Use the space behind the motherboard tray to hide excess cables.
Bundle cables together with zip ties or Velcro straps, keeping them clear of fans and other moving parts.
2. Connect All Cables:
Connect the 24-pin ATX cable to the motherboard’s main power connector.
Connect the 8-pin (or 4+4 pin) CPU power cable to the motherboard’s CPU power connector.
Connect the SATA power and data cables to your storage drives.
Connect the front panel connectors (power switch, reset switch, LED indicators) to the corresponding pins on the motherboard.
3. Final Checks:
Double-check all connections, ensuring everything is secure and correctly plugged in. Look for any loose cables or potential obstructions to airflow.
I. Connecting Front Panel Connectors
1. Power Button, Reset Button, and LEDs:
Locate the front panel connector pins on the motherboard, usually near the bottom edge.
Refer to the motherboard manual to identify the correct pins for the power button, reset button, HDD LED, and power LED. Connect the small cables from the case to these pins.
2. USB Ports and Audio Jacks:
Connect the front panel USB ports (USB 2.0, USB 3.0, or USB-C) to the corresponding headers on the motherboard.
Connect the front panel audio jacks to the motherboard’s audio header, usually located near the rear I/O area.
3. Test the Connections:
Before closing the case, double-check that all front panel connectors are correctly attached. Misplaced connectors can prevent the PC from powering on or cause other issues.
J. Powering On and Testing
1. Plug in the Power Cable:
Connect the power cable to the PSU and then to a wall outlet or surge protector.
2. Initial Power-On:
Press the power button on the case. If all connections are correct, your PC should power on, and you should hear fans spinning and see lights on the motherboard or case.
3. Enter the BIOS/UEFI:
Immediately after powering on, press the designated key (usually Delete, F2, or F10) to enter the BIOS/UEFI.
Check that the CPU, RAM, and storage drives are detected correctly. If something isn’t recognized, power off and double-check the connections.
4. Monitor Temperatures:
While in the BIOS/UEFI, check the CPU temperature to ensure the cooler is working properly. Idle temperatures should typically be below 40°C. If the temperatures are unusually high, double-check the cooler installation.
5. Troubleshoot If Necessary:
If the PC doesn’t power on or there are issues, consult the troubleshooting section of your motherboard manual. Common problems include loose connections, improperly seated RAM or GPU, or front panel connector issues.
With these steps, your PC should now be fully assembled and ready for the next phase: installing the operating system and software. Taking your time during the assembly process ensures that everything is properly connected, which reduces the risk of errors or damage and sets the stage for a reliable, high-performing machine.