PC Build Compatibility Checklist: What Has to Fit What
The checks that decide whether PC parts work together: socket, memory, case size, cooler, graphics card length, power supply and storage, with plain examples.
In short: Check the processor socket against the motherboard, the memory type, the board size against the case, graphics card length, cooler height or radiator size, power supply wattage and form, and storage slots. Our builder checks all of these as you choose.
Most of the fear in building a PC comes from one question: will this part fit with that one? The answer is a short list of checks. Our builder runs all of them as you choose and again at checkout, but it helps to know what they are and why, especially if you are comparing parts elsewhere.
1. Processor socket and motherboard
A processor only fits a motherboard with the same socket. AMD's current desktop processors use AM5, and Intel's use LGA1851 or, for older chips, LGA1700. A processor on the wrong socket will not even seat in the board. This is the first check and the one that rules out the most mistakes.
2. Memory type and slots
DDR4 and DDR5 memory are not interchangeable: the notches are in different places, so a stick of one will not fit a slot for the other. A board takes one type only. Also check the number of modules: a kit of two sticks needs two free slots, and a four-stick kit needs a board with four.
3. Case size and motherboard size
Motherboards come in sizes: ATX is the standard, mATX is smaller, and ITX is very small. A case lists the sizes it accepts. A smaller board fits a bigger case, but a bigger board never fits a smaller one.
4. Graphics card length
Graphics cards are long and getting longer. Every case lists the longest card it can hold, in millimetres, and a card that is even a few millimetres over simply does not go in. Small cases are the ones to watch.
5. The cooler
Three things matter:
- The socket. The cooler's mounting kit must support your processor's socket.
- The rating. The cooler must be rated for at least the heat the processor produces. An undersized cooler makes the processor slow itself down.
- The fit. An air cooler has a height, and the case has a limit on it. A liquid cooler has a radiator size, and the case must have a place to mount a radiator of that size, usually at the front or the top.
6. The power supply
Two checks again. First, the shape: most cases take a standard ATX power supply, and small cases take the smaller SFX kind. Second, the wattage: it must cover the processor and the graphics card with some room to spare. The guide to sizing a power supply shows how we work that out.
7. Storage
Fast NVMe drives sit on the motherboard in M.2 slots, and boards have a limited number, so count them if you want more than one or two. Older-style SATA drives, including large hard drives, need a drive bay in the case, and cases have a fixed number of those.
8. A processor without built-in graphics
Some processors, usually the ones with an F in the name, have no graphics of their own. They need a graphics card to show anything on a screen. The builder flags this, and does not let you check out without one.
What the builder does with all this
As you pick parts, it greys out options that clash with parts you chose earlier, and it says why in plain words. If you change an early part, such as the case, it swaps later parts that no longer fit for the closest ones that do, and tells you what changed. At checkout the whole configuration is checked again on our side, so a mismatch cannot slip through.
What it cannot check for you
Taste and priorities. Fans, lighting, noise and looks are your call, and so is how much you spend where. Start from a ready-made build if you want a balanced default, then change what matters to you.
Paying with crypto? See the guide to buying a gaming PC with Bitcoin, or compare a custom build with a prebuilt.