What you need to know before you start
Building a computer from scratch means buying individual parts — a processor, motherboard, memory, storage, power supply, and case — then assembling them yourself. You do not need special training or tools beyond a screwdriver and an anti-static wrist strap. Most people spend between two and four hours on their first build, and the main risk is installing a part incorrectly, which you can fix by reinstalling it.
The real decision is whether building makes sense for your situation. Building costs less than buying a pre-built computer with the same performance, but only if you know what parts to buy. If you want a computer for a specific task — gaming at high settings, video editing, everyday browsing — building lets you choose parts that match that task instead of paying for features you will not use. If you just need something that works and do not want to research parts, buying pre-built is simpler.
Key Takeaways
- You will need a processor, motherboard, memory (RAM), storage drive, power supply, case, and a way to install Windows or Linux — budget roughly $500 to $2,000 depending on what you want the computer to do.
- The motherboard determines which processor and memory you can use, so choose the motherboard first, then buy compatible parts.
- Installation order matters: install the power supply in the case first, then the motherboard, then memory and storage, then the processor last.
- You will need to enter the BIOS after assembly to set the boot drive and enable XMP memory settings, which takes about 10 minutes.
- Watch a video walkthrough of your specific motherboard model before you start — every board has connectors in slightly different places.
Choosing parts that work together
The motherboard is the foundation. It has a socket that accepts only one type of processor — an Intel LGA1700 socket, for example, or an AMD AM5 socket. Once you pick a motherboard, you must buy a processor that fits that socket. The same applies to memory: a motherboard supports a specific memory type, usually DDR5 or DDR4, and a maximum amount, usually 192GB or more for modern boards.
Start by deciding your budget and what you want to do. A $600 computer handles web browsing, email, and office work. A $1,200 computer plays modern games at high settings. A $2,000 computer edits video or runs design software. Once you know your budget, use a parts compatibility checker like PCPartPicker to build a list. Enter each part as you choose it, and the site will warn you if parts do not fit together — incompatible memory, a processor that does not fit the socket, a power supply too weak for your graphics card.
The graphics card is optional. If you choose a processor with integrated graphics — most Intel and AMD processors include this — you can skip the graphics card and use the processor's built-in video output. If you want to play games or do graphics work, buy a dedicated graphics card. The power supply must be strong enough for your parts; a system with a high-end graphics card might need 850 watts, while a system without one might need only 550 watts.
What to buy and where to find it
The main parts retailers are Newegg, Amazon, Best Buy, and Micro Center. Prices vary between them, so check two or three before you buy. Micro Center often has the lowest prices on processors and motherboards if you have one nearby. Amazon and Newegg ship nationwide. Best Buy carries mid-range parts in stock but usually charges more.
Watch for sales on the parts you need. Processors and motherboards rarely drop in price, but memory and storage go on sale regularly. Graphics cards fluctuate based on demand. If you are not in a hurry, waiting a week or two for a sale can save $50 to $200. Do not wait for a "perfect" price — parts are always getting cheaper, and waiting months costs you months of use.
Buy all your parts before you start assembly. If you discover a part is missing or broken during assembly, you will have to stop and wait for a replacement. Order everything at once so it arrives together, or at least order the core parts — processor, motherboard, memory, and case — before you start.
Setting up your workspace and tools
You need a clean, flat surface with good lighting. A dining table or desk works fine. Avoid carpet if you can; if you must work on carpet, wear an anti-static wrist strap clipped to a metal part of the case. The strap prevents static electricity from damaging sensitive components. You can buy one for $5 to $10 at any electronics store.
Gather a Phillips-head screwdriver — most computer screws are Phillips-head, and the screws are small, so a precision screwdriver works better than a regular one. You will also need the motherboard manual. Download it from the motherboard manufacturer's website before you start; you will refer to it constantly to find where connectors go. Print it or open it on a phone or tablet next to your workspace.
Unbox all your parts and lay them out. Check that everything arrived. Look for any obvious damage — bent pins on a processor, cracked plastic on a memory stick. If something looks wrong, contact the seller before you install it.
Installing parts in the correct order
Install the power supply first. Open the case and locate the power supply bay, usually at the bottom rear. Slide the power supply in with the fan facing down if your case has ventilation holes in the bottom, or facing up if it does not. Screw it in with four screws. Do not plug it in yet.
Install the I/O shield next. This is a thin metal plate that comes with the motherboard and fits into the rectangular opening at the rear of the case. Push it in from inside the case until it clicks into place. Install the motherboard standoffs — small brass spacers that screw into the case to hold the motherboard at the right height. Line them up with the holes in your motherboard, then place the motherboard on top and screw it down. Do not overtighten; snug is enough.
Install memory and storage while the motherboard is still easy to reach. Push the memory sticks straight down into the memory slots until the clips on both ends snap closed. Install the storage drive — an M.2 SSD usually goes into a slot on the motherboard itself, while a 2.5-inch SSD or 3.5-inch hard drive goes into a bay in the case. Screw it down with one or two screws.
Install the processor last. Lift the retention mechanism on the processor socket, align the processor with the socket, and lower it straight down. Do not force it; it should slide in smoothly. Lower the retention mechanism to lock it in place. Install the CPU cooler according to its instructions — this varies widely between models, so follow the manual that came with the cooler.
Connecting power and data cables
Connect the 24-pin power connector from the power supply to the motherboard. This is the largest connector and goes into the largest socket on the board, usually on the right side. Connect the 8-pin CPU power connector near the processor socket. Connect SATA power cables to any 2.5-inch or 3.5-inch drives. If you have a graphics card, connect the PCIe power connectors — usually 6-pin or 8-pin connectors from the power supply.
Connect data cables next. M.2 SSDs do not need data cables; they plug directly into the motherboard. SATA drives need SATA data cables from the motherboard to the drive. Connect the front-panel connectors — the power button, reset button, and LED lights on the front of the case — to the small pins on the motherboard. These are labeled in the motherboard manual and are easy to get wrong, but getting them wrong just means the power button will not work; it will not damage anything.
Double-check every connection. Loose power connectors are the most common reason a new build does not turn on. Make sure the 24-pin and 8-pin connectors are fully seated.
Turning on and configuring your computer
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 front of the case. The computer should turn on, fans should spin, and lights should come on. If nothing happens, turn it off, check that the 24-pin and 8-pin power connectors are fully seated, and try again.
If the computer turns on, let it run for a minute to make sure nothing overheats or smells wrong. Then turn it off and install your graphics card if you have one. Push it straight down into the PCIe slot until it clicks, then screw the bracket to the case. Turn the computer back on.
You will see a logo on the screen and a prompt to enter the BIOS. Press Delete or F2 — the screen will tell you which key. In the BIOS, set the boot drive to your storage drive, enable XMP memory settings if your memory supports it, and save and exit. The computer will restart and begin installing Windows or Linux. Follow the on-screen prompts to complete the installation.
Frequently Asked Questions
Do I need thermal paste between the processor and cooler?
Most modern coolers come with thermal paste pre-applied to the base. If yours does not, you need a thin layer of thermal paste between the processor and cooler. Apply a small pea-sized dot to the center of the processor, then install the cooler. Too much paste is worse than too little.
What if my computer does not turn on?
Check the 24-pin and 8-pin power connectors first — they are the most common culprit. Make sure the power supply switch is on. Verify that the power button connector is plugged into the motherboard correctly. If the computer still does not turn on, reseat the memory sticks and try again.
Can I install the graphics card after I build the computer?
Yes. You can build and test the computer with integrated graphics, then add a graphics card later. Just turn off the computer, unplug it, install the card, and turn it back on. You may need to update drivers after installation.
How long does it take to install Windows?
Windows installation takes 15 to 30 minutes depending on your storage drive speed and internet connection. After installation, Windows will download and install updates, which can take another 30 minutes to an hour. Plan for at least two hours from power-on to a usable desktop.
What should I do if a part arrives broken?
Contact the retailer immediately with photos of the damage. Most retailers will replace the part or issue a refund without requiring you to return the broken part first. Do not install a visibly damaged part; it may fail during use or damage other components.