PC Builder Compatibility Checklist

For anyone assembling a parts list for a first build. Compatibility in a desktop PC is not mysterious, it is about eight specific things lining up, and a part that fails any one of them will not work no matter how good it is. Work down the list in this order.

ZillaKit team · Published September 2026

A PC build fails compatibility in one of two ways. Electrically, where a part physically cannot connect or is not supported by the board. Or physically, where the part simply will not fit in the space available. Beginners worry a lot about the first and get caught by the second, because clearance problems only reveal themselves when the box is already open on the kitchen table.

The order below matters. Each check constrains the next, so working top to bottom means you rarely have to go back and change something.

1. CPU socket and chipset

The socket is the physical interface between the processor and the motherboard. A processor made for one socket will not go into another, and there is no adapter. This is the first decision because it splits the entire parts market in two.

The socket alone is not sufficient, though. The motherboard's chipset determines which processors the board actually supports within that socket, and manufacturers frequently support several processor generations on one socket with different chipsets. Every motherboard maker publishes a CPU support list for each board model. Find your exact board model, find your exact processor on that list, and check the required firmware version noted beside it.

That firmware note is the trap. A board can be listed as supporting a processor only after a firmware update, and if the board shipped with older firmware it will not start with that processor installed. Some boards can update firmware without a working processor fitted; many cannot. If your combination depends on an update, either buy a board that ships with the newer firmware or plan a way to perform the update.

2. Memory generation and configuration

DDR4 and DDR5 modules are keyed differently and will not fit in each other's slots. A motherboard supports one or the other, never both, so this is decided the moment you pick the board. Check the board's memory support page for the maximum capacity, the number of slots, and the speeds it will actually run.

Two practical points beyond the generation. Populate slots in the pairs the manual specifies, usually the second and fourth slot when fitting two modules, so the memory runs in dual channel. And be aware that advertised high memory speeds usually require enabling a profile in firmware; out of the box, memory often runs at a slower default. Neither of these is a compatibility failure, but both cost performance silently.

3. Motherboard form factor versus case

ATX, Micro-ATX and Mini-ITX are the three sizes you will meet, largest to smallest. A case lists which form factors it accepts. A smaller board goes into a larger case fine; the reverse does not work. Choosing a small case early is the most common way people paint themselves into a corner, because small cases constrain cooler height, graphics card length and power supply size all at once.

4. CPU cooler height

Air coolers are specified in millimetres of height. Cases are specified with a maximum CPU cooler clearance, also in millimetres. Cooler height must be less than case clearance, with a few millimetres spare, because published figures are sometimes measured optimistically.

Two extra things to check on the cooler. First, that it includes a mounting bracket for your socket, since some coolers require a separately purchased kit. Second, memory clearance: large air coolers overhang the nearest memory slot, and tall memory modules with heatsinks will not fit underneath. If you are using a big cooler, choose low profile memory.

For a liquid cooler, the question changes to radiator size. The case lists supported radiator sizes by location, typically front, top and rear. Check the thickness too, including fans, because a thick radiator mounted in the top can collide with the motherboard heatsinks.

5. Graphics card length, width and slots

Cards are specified by length in millimetres and by thickness in expansion slots. Modern high end cards are long and frequently three slots thick.

Any modern graphics card fits electrically in a standard PCI Express x16 slot, so this check is almost entirely about physical space.

6. Power supply: wattage, connectors and size

Three separate questions here and people usually only ask the first.

Wattage needs to cover the total draw of your parts with headroom. That deserves its own treatment, so see the power supply guide linked below.

Connectors are the check that catches people out. Your graphics card needs a specific set of supplementary power connectors, and the supply must physically have them. Adapters exist but chaining several from one cable is how supplies get overloaded. If the card requires a modern high power connector, make sure the supply provides it natively rather than through a converter.

Physical size matters in small cases. Standard ATX supplies come in varying depths, and compact cases often require a shorter unit or the smaller SFX format.

7. Storage: slot count and interface

Count the M.2 slots on the board and check what each supports, because they are not always identical. Some slots take only NVMe drives, some also take SATA M.2 drives, and the interface speed can differ between the slot nearest the processor and the others.

There is also a sharing behaviour worth knowing: on many boards, populating a particular M.2 slot disables one or two SATA ports. The manual states this plainly in a table, and it is the kind of detail that is very annoying to discover after you have installed six drives.

8. Case front panel and fan headers

The last check is small but real. If your case has a front USB Type-C port, the motherboard needs the matching internal header or that port will not work. Count your fans against the board's fan headers, and buy a splitter or hub in advance if you are short.

Using a builder to do the bookkeeping

Holding eight constraints in your head while browsing parts is where errors creep in. The PC Builder keeps track of the selected parts and flags socket mismatches, insufficient wattage and clearance problems as you go, which turns the checklist into something you verify rather than something you have to remember. Use it to narrow the list, then confirm the final combination against the motherboard manufacturer's own support pages before you buy.

Honest limits

No automated compatibility checker is complete. Databases lag behind new releases, published clearance figures are sometimes measured generously, and edge cases like a particular cooler fouling a particular board's heatsink are only documented by people who have hit them. For an unusual combination, a quick search for your exact two part names together is worth sixty seconds.

Compatibility also says nothing about balance. A parts list can pass every check here and still be a poor build, for example a top end graphics card paired with a processor that cannot keep up with it. Getting the parts to work together is the floor, not the goal.

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