What you actually need to build a working computer

A functioning PC needs seven parts: a motherboard, a CPU (processor), RAM (memory), a storage drive, a power supply, a case, and a graphics card (or integrated graphics built into your CPU). Everything else — cooling fans, extra USB ports, RGB lighting — improves performance or appearance but is not required to turn the machine on. If you skip any of these seven, your PC will not start.

The parts must be compatible with each other. A CPU designed for an Intel motherboard will not fit an AMD motherboard. RAM designed for older systems will not work in newer ones. A power supply too weak for your components will shut down under load. This guide walks you through each part, what it does, and how to avoid the most common mismatch.

Key Takeaways

  • Your motherboard determines which CPU, RAM, and graphics card will physically fit, so choose it first or verify compatibility before buying other parts.
  • A CPU and motherboard must match in socket type — an Intel Core i5 requires an Intel motherboard with the right socket, not an AMD board.
  • RAM speed and type must match your motherboard; DDR4 RAM will not work in a DDR5 motherboard, and buying faster RAM than your board supports wastes money.
  • Your power supply wattage must exceed the total power draw of your CPU, graphics card, and storage combined, with headroom for efficiency loss.
  • A graphics card is optional only if your CPU has integrated graphics; most CPUs do not, so budget for a dedicated card unless you are building for office work or light browsing.

The motherboard: the part that holds everything else

The motherboard is the circuit board that every other part plugs into. It determines which CPU you can use, which type of RAM fits, and which graphics card will work. If you choose the motherboard first, the other parts follow. If you choose the CPU first, the motherboard must match it.

Motherboards come in three sizes: ATX (full-size, most common), Micro-ATX (smaller), and Mini-ITX (smallest). The size affects how many expansion slots you have and what case you need. For a first build, ATX is the safest choice because cases and power supplies are designed around it.

The motherboard also has a socket — the physical slot where the CPU plugs in. Intel and AMD use different sockets. Within each brand, older and newer sockets are incompatible. An Intel LGA1700 socket (current as of 2024) will not accept an older LGA1200 CPU. Before buying a motherboard and CPU separately, verify they share the same socket on the manufacturer's website or a compatibility checker.

The CPU: the processor that does the work

The CPU (central processing unit) is the brain of your computer. It runs programs, handles calculations, and determines how fast your PC performs everyday tasks. The two main brands are Intel (Core i3, i5, i7, i9) and AMD (Ryzen 3, 5, 7, 9). Within each brand, higher numbers mean more power and higher cost.

For office work, web browsing, and video playback, an entry-level CPU like an Intel Core i3 or AMD Ryzen 3 is sufficient. For gaming, video editing, or running multiple heavy programs at once, a mid-range CPU like an i5 or Ryzen 5 is more practical. High-end CPUs (i7, i9, Ryzen 7, 9) are for professional work or extreme gaming setups.

The CPU comes with a cooler — a fan and heatsink that sits on top and pulls heat away. Most retail CPUs include a basic cooler in the box. You only need to buy a separate cooler if you plan to overclock (push the CPU beyond its standard speed) or if the included cooler is too loud for your taste.

RAM: the temporary memory your programs use

RAM (random-access memory) is temporary storage that your CPU uses while running programs. More RAM lets you run more programs at once without slowdown. RAM comes in two types: DDR4 and DDR5. Your motherboard accepts one or the other — they are physically different and not interchangeable.

For office work and browsing, 8 GB of RAM is the minimum. For gaming or light video editing, 16 GB is standard. For professional video editing, 3D rendering, or running virtual machines, 32 GB or more is practical. Buying more RAM than your motherboard supports is wasted money — a DDR4 motherboard will not accept DDR5 RAM no matter how much you spend.

RAM also has a speed rating in MHz (megahertz). DDR4 typically runs at 3000–3600 MHz, and DDR5 at 4800–6000 MHz. Faster RAM costs more but gives a small performance boost. For most builds, standard-speed RAM for your motherboard type is the best value.

Storage: where your files and programs live

A storage drive holds your operating system, programs, and files permanently. There are two types: SSDs (solid-state drives) and HDDs (hard disk drives). SSDs are faster, more reliable, and have no moving parts. HDDs are cheaper per gigabyte but slower and more prone to failure. For a new build, an SSD is the only practical choice.

SSDs come in different sizes. A 500 GB drive holds Windows and a few programs but fills quickly. A 1 TB drive is the practical minimum for most people. A 2 TB drive gives comfortable room for programs, games, and files. If you need more space, you can add a second drive later.

SSDs also connect to the motherboard in different ways. Most modern SSDs use NVMe (a fast connection that looks like a small stick) and plug directly into an M.2 slot on the motherboard. Older SSDs use SATA (a slower connection) and require a cable. Check your motherboard's manual to see which slots it has. NVMe is faster and cleaner, so it is the standard for new builds.

The power supply: the part that delivers electricity

The power supply converts wall electricity into the right voltage and current for your components. It must have enough wattage to handle your CPU, graphics card, and storage drive combined, plus headroom for efficiency loss and power spikes.

To estimate wattage, add the power draw of your CPU (usually 65–125 watts), your graphics card (usually 150–450 watts), and other components (usually 50–100 watts combined). Then add 20–30 percent as headroom. A system with a mid-range CPU and graphics card typically needs 650–750 watts. A high-end gaming system might need 850–1000 watts. Undersizing the power supply causes crashes and hardware damage. Oversizing is harmless and costs only a little more.

Power supplies also have a certification rating: Bronze, Gold, Platinum, or Titanium. Higher ratings mean the supply wastes less electricity as heat. A Gold-rated supply is the practical choice — it costs a little more than Bronze but saves money on your electric bill over time. Avoid no-name or very cheap power supplies; they fail more often and can damage your other parts.

The graphics card: optional only if your CPU has integrated graphics

A graphics card (also called a GPU) renders images and video. Some CPUs have integrated graphics built in — they can display video without a separate card. Most CPUs do not. If your CPU lacks integrated graphics, you must buy a dedicated graphics card or your PC will not display anything on a monitor.

For office work and video playback, integrated graphics are enough. For gaming, video editing, or 3D work, a dedicated graphics card is necessary. The two main brands are NVIDIA (GeForce RTX series) and AMD (Radeon RX series). Entry-level cards (RTX 4060, RX 6600) handle 1080p gaming at good frame rates. Mid-range cards (RTX 4070, RX 6700) handle 1440p gaming. High-end cards (RTX 4090, RX 7900 XTX) are for 4K gaming or professional work.

Graphics cards plug into a slot on the motherboard called a PCIe slot. Most modern motherboards have at least one. Check your motherboard manual to confirm it has a free PCIe slot before buying a card. Also verify your power supply has the right connectors — most modern cards need 6-pin or 8-pin power connectors from the power supply.

The case: the box that holds everything

The case is the metal box that holds all your parts. It provides mounting points for the motherboard, drive bays for storage, and airflow to keep components cool. Cases come in sizes that match motherboard sizes: ATX cases for ATX motherboards, Micro-ATX cases for Micro-ATX boards, and so on. Putting an ATX motherboard in a Micro-ATX case will not fit.

Cases also vary in cooling design. Some have multiple built-in fans, others have none. A case with at least two fans (one pulling air in, one pushing air out) is practical for most builds. Cases with poor airflow cause components to overheat and throttle performance or shut down.

For a first build, choose a case designed for beginners — they have clear instructions, good cable management space, and room to work. Avoid very cheap cases with sharp edges and poor ventilation. A mid-range case costs $50–100 and will serve you well for years.

Frequently Asked Questions

Do I need a graphics card if my CPU has integrated graphics?

No. If your CPU has integrated graphics (check the manufacturer's specs), you can display video without a separate card. You can add a graphics card later if you want to game or do graphics work. Most current CPUs do not have integrated graphics, so budget for a card unless you specifically chose a CPU with them.

What happens if my power supply is too weak?

Your PC will shut down suddenly under load, often during gaming or video editing when power draw peaks. Repeated shutdowns can corrupt files and damage components. If your power supply is undersized, replace it before building — it is cheaper than replacing damaged parts later.

Can I use DDR4 RAM in a DDR5 motherboard?

No. DDR4 and DDR5 RAM are physically different and not interchangeable. Your motherboard accepts one type or the other. Check your motherboard manual or the seller's listing to confirm which type it uses before buying RAM.

What if my CPU and motherboard have different sockets?

They will not work together. The CPU will not physically fit in the motherboard's socket. Before buying, verify the socket type on both the CPU and motherboard — Intel LGA1700, AMD AM5, and others are common. A compatibility checker on PCPartPicker or the manufacturer's website will confirm a match in seconds.

Is a more expensive case worth it?

A mid-range case ($50–100) offers good airflow, cable management, and ease of assembly. Very cheap cases have poor ventilation and sharp edges. Very expensive cases ($200+) add features like tempered glass panels and RGB lighting that do not affect performance. For a first build, a mid-range case is the best value.