The core parts every PC needs to work

A working PC needs five things: a motherboard (the main circuit board that everything plugs into), a CPU or processor (the chip that does the thinking), RAM or memory (the fast temporary storage the CPU uses while working), a power supply (the box that converts wall power into the right voltage for each part), and a storage drive (where your files and programs actually live). Without any one of these five, your PC will not turn on or will not do anything useful.

You also need a case — the metal or plastic box that holds everything and keeps dust out. The case is not optional; loose parts on a desk will short out and break. Finally, you need a way to see what the computer is doing. Most modern CPUs have built-in graphics, so you can plug a monitor directly into the motherboard. If you want better graphics for gaming or video work, you can add a separate graphics card, but it is not required to make the PC work.

Key Takeaways

  • Five parts are non-negotiable: motherboard, CPU, RAM, power supply, and storage drive — the PC will not function without all five.
  • A case is required to protect the parts from damage and dust, even though it does not do any computing itself.
  • Most CPUs include built-in graphics, so you do not need a separate graphics card unless you are gaming or doing graphics-heavy work.
  • The motherboard you choose determines which CPU, RAM type, and power supply wattage will work with it, so pick the motherboard first.
  • Cooling — either the fan that comes with the CPU or an aftermarket cooler — is essential because a CPU will shut itself down or burn out if it overheats.

How the motherboard limits your other choices

The motherboard is the decision that cascades to everything else. It has a specific socket — a physical slot where only certain CPUs fit. An Intel motherboard with an LGA1700 socket will not accept an AMD Ryzen CPU. The motherboard also determines what type of RAM you can use: DDR5, DDR4, or older DDR3. If you buy a motherboard that uses DDR5, you must buy DDR5 RAM, or it will not work at all.

The motherboard also tells you the minimum power supply wattage you need. A motherboard designed for high-end CPUs and graphics cards might require a 750-watt power supply, while a budget build might work with 450 watts. Check the motherboard's manual or product page for the recommended wattage before you buy the power supply. Buying a power supply that is too weak will cause crashes or prevent the PC from starting.

CPU and cooling — they work as a pair

The CPU is the processor — the chip that runs your programs. It generates heat while it works, and if it gets too hot, it will throttle (slow itself down) or shut down to protect itself. Every CPU comes with a basic cooler in the box, usually a fan mounted on top of the CPU with a metal plate underneath. This cooler is enough for normal use like web browsing, email, and office work.

If you are gaming, streaming, or doing video editing, the CPU will run hotter, and the stock cooler may not be enough. In that case, you can buy an aftermarket cooler — a larger fan or a liquid cooling system — that pulls heat away faster. The cooler you choose must fit your CPU socket and fit inside your case. Check the case dimensions and the cooler dimensions before you buy, because a tall cooler can hit the side panel or RAM sticks and not fit.

RAM: how much and what type

RAM is temporary memory the CPU uses while programs are running. More RAM lets you run more programs at once without slowdowns. For basic use — browsing, email, documents — 8 GB is the minimum. For gaming or light creative work, 16 GB is standard. For video editing, 3D rendering, or running many programs at once, 32 GB or more is worth considering.

RAM comes in sticks, usually 8 GB or 16 GB each. Most motherboards have two or four RAM slots. If your motherboard has four slots and you buy two 16 GB sticks, you can add two more later without replacing what you have. If you buy four 8 GB sticks now, you are full and cannot expand. Think about whether you might want to add more RAM in the future, because it is cheaper to buy it now than to buy it later and throw away what you already have.

Storage: SSD versus HDD, and how much space

Your storage drive is where Windows, your programs, and your files live permanently. An SSD (solid-state drive) is much faster than an HDD (hard disk drive). An SSD will boot Windows in 10 to 20 seconds; an HDD takes 30 to 60 seconds. Programs launch faster on an SSD. The trade-off is price: SSDs cost more per gigabyte than HDDs.

For a new PC, buy an SSD for your main drive. A 500 GB SSD is the minimum if you are only storing Windows and a few programs. A 1 TB SSD is more comfortable and costs only slightly more. If you need lots of storage for video files, photos, or games, you can add a second drive later — either another SSD or an HDD for cheaper bulk storage. The motherboard will have at least one M.2 slot (the fast connection type) and usually one or two SATA slots (the older, slower connection type).

Power supply: wattage and efficiency rating

The power supply converts AC power from your wall outlet into the DC power each component needs. It has a wattage rating — 450W, 650W, 750W, and so on. The wattage must be higher than the total power draw of all your parts combined, with some headroom. A CPU and motherboard might draw 150 watts under load, a graphics card might draw 300 watts, and other parts another 50 watts. That is 500 watts total, so a 650-watt power supply gives you 150 watts of headroom and is a safe choice.

Power supplies also have an efficiency rating: Bronze, Gold, Platinum, or Titanium. A Gold-rated supply converts about 90% of wall power into usable power; a Bronze-rated supply converts about 85%. The difference shows up in your electricity bill over years. A Gold-rated supply costs more upfront but saves money over time. For most people, Gold is a good balance. Do not buy the cheapest power supply you can find — a failing power supply can damage or destroy other parts.

Case: size, airflow, and cable management

The case holds everything and protects it from dust and accidental damage. Cases come in different sizes: full tower, mid tower, and mini ITX. A full tower is large and straightforward to work in. A mid tower is the most common and fits most builds. A mini ITX case is small and portable but harder to build in and may not fit large coolers or graphics cards.

Airflow matters because heat needs to escape. A case with intake fans in the front and exhaust fans in the back will keep temperatures lower than a case with no fans. Most cases come with one or two fans; you can add more if you want. Cable management — routing cables neatly so they do not block airflow — is easier in some cases than others. If you care about how the inside looks, read reviews that show photos of the inside before you buy.

Graphics card: when you need one and when you do not

Modern CPUs from Intel and AMD include built-in graphics. If you are browsing the web, working in documents, or watching videos, the built-in graphics are fine. You do not need a separate graphics card. If you are gaming, the built-in graphics will not be fast enough for most games at good settings. A graphics card plugs into a PCIe slot on the motherboard and has its own memory and cooling.

Graphics cards are expensive and use a lot of power. A mid-range card might cost $200 to $400 and draw 200 to 300 watts. A high-end card can cost $600 or more. If you are building a gaming PC, the graphics card is usually the biggest expense. If you are not gaming, skip it and save the money. You can always add one later if you change your mind.

Frequently Asked Questions

Do I need to buy Windows separately, or does it come with the PC?

Windows does not come with the parts. You buy a Windows license separately from Microsoft. You can install Windows for free and use it without a license, but you will see a watermark on the desktop and cannot customize some settings. A Windows 11 Home license costs around $120. You install it from a USB drive you create on another computer.

What if I buy parts that do not work together?

The most common mismatch is buying a CPU that does not fit the motherboard socket, or RAM that is the wrong type for the motherboard. Check the motherboard manual or product page before you buy. Another common mistake is buying a cooler that is too tall for the case. Measure your case height and the cooler height before you buy. Most online retailers let you return parts within 30 days if they do not work.

Is it cheaper to build a PC or buy one already built?

Building your own is usually cheaper because you skip the labor and markup a store adds. You also get to choose exactly which parts you want instead of accepting a pre-built combination. The trade-off is that building takes a few hours and requires following instructions carefully. If you are not comfortable with that, a pre-built PC from a reputable brand may be worth the extra cost.

How much should I spend on a PC build?

A basic PC for web browsing and office work costs $400 to $600. A gaming PC costs $1000 to $2000 depending on how fast you want it. A workstation for video editing or 3D rendering can cost $2000 or more. Start with what you actually need the PC to do, then pick parts that match that need. Do not overspend on a graphics card if you are not gaming, and do not skimp on the power supply or storage.

Can I upgrade parts later, or do I have to buy everything at once?

You can upgrade most parts later: RAM, storage drives, graphics card, and cooler. The CPU and motherboard are harder to upgrade because changing the CPU usually means changing the motherboard too. Buy a motherboard with room to grow — extra RAM slots, extra drive slots, and a power supply with headroom — so you can add parts without replacing what you have.