The motherboard is the component people most often overspend on, and occasionally the one they underspend on in a way that causes real problems. It does not make a machine faster. What it decides is what fits, what connects, and what you can add later.
In short
- The socket is decided by your processor. That comes first and narrows everything else.
- Chipset determines features and connectivity, not speed.
- Count the M.2 slots and USB ports you actually need, then read the manual on lane sharing.
- Power delivery matters for high-power processors and is largely irrelevant for modest ones.
Socket, then chipset
The socket has to match the processor. This is absolute: there is no adapter, and a mismatch means the parts do not join.
The chipset sits below that and determines features: how many PCIe lanes are available, how many USB ports, whether you can overclock, how many M.2 slots the board can offer. It does not make anything faster.
Mid-tier chipsets, B650 on AM5 or B760 on LGA1700, cover what most builds need. The top tier adds more lanes and more connectivity, which matters if you are filling the board with drives and cards, and otherwise does not.
Size, and what you give up
ATX is the full size: most slots, most ports, easiest to work in.
Micro-ATX is shorter, usually with one fewer expansion slot. For a build with one graphics card and no other cards, you rarely notice the difference, and boards are often cheaper.
Mini-ITX is small and carries real constraints: two memory slots rather than four, one expansion slot, fewer M.2 slots, and a price premium. Choose it because you want a small machine, not to save money.
A smaller board generally fits a larger case, but check the case lists the size. E-ATX is the exception: the name covers several widths rather than one standard, so a case must name E-ATX explicitly to be safe.
Lane sharing, the specification nobody reads
Boards advertise three or four M.2 slots and six SATA ports. What the advertisement rarely says is that some of those share the same chipset lanes, so populating one disables another.
The manual has a table showing which combinations conflict, usually near the storage section. It is worth reading before buying if you plan several drives, because discovering it afterwards means unplugging something that was working.
Power delivery
The voltage regulator modules on a board convert incoming power to what the processor needs. A board with weak power delivery paired with a high-power processor will run hot and may reduce clock speeds to stay within limits.
This is a genuine concern for high-core-count processors and a largely manufactured one for modest chips. A mid-range board from a known manufacturer handles a mid-range processor without difficulty. The elaborate heatsinks on expensive boards are mostly addressing a problem those builds do not have.
Check the CPU support list for your exact board model before buying, particularly when pairing a recently released processor with a board that has been on sale for a while. A firmware update may be needed, and applying it can require a processor the board already supports unless it offers BIOS flashback.