Choosing PC Parts That Work Together

These two decide how fast the PC is and take most of the budget. Everything else is chosen to fit them. For gaming the graphics card matters most; for rendering, compiling or heavy multitasking the processor does.

If you would rather not do this by hand, the build planner takes a budget and a use and picks a complete set that passes every check below, using live prices.

A processor only fits a motherboard with the same socket. Each platform also takes one type of memory, which matters for the next step.

• AMD AM5: Ryzen 7000, 8000 and 9000 series. DDR5 memory only.
• AMD AM4: Ryzen 1000 to 5000 series. DDR4 memory only. Older boards may need a BIOS update for Ryzen 5000.
• Intel LGA1851: Core Ultra 200S series. DDR5 memory only.
• Intel LGA1700: 12th, 13th and 14th gen Core. Each board takes either DDR4 or DDR5, never both, so check which.

Within a socket, the chipset (B850, X870, Z890 and so on) sets the features: how many fast M.2 slots, USB ports, and whether the processor can be overclocked. A chipset belongs to one socket only, so a B850 board is always AM5 and a B860 board is always LGA1851, despite the similar names.

• Match the type to the board: DDR4 and DDR5 are physically different and will not fit each other's slots.
• Buy desktop memory, not laptop memory (SO-DIMM), which is shorter and will not fit.
• Two sticks rather than one, so it runs in dual channel. A kit of two is sold matched.
• 16 GB is the practical minimum for gaming today, and 32 GB is common in new builds.

The speed on the box only applies once XMP or EXPO is switched on in the BIOS. Without it, all memory runs at a slower standard speed.

Motherboards come in three common sizes: ATX (full size), Micro-ATX and Mini-ITX. A case lists the sizes it takes, and a bigger case takes smaller boards, so an ATX case fits all three but a Mini-ITX case fits only Mini-ITX.

• Graphics card length against the case's maximum GPU length. Modern cards can be over 330 mm long.
• Cooler height against the case's maximum CPU cooler height. Big tower coolers are often 155 to 165 mm.
• Radiator size (240, 280, 360 mm) against the case's radiator support, if you use an all-in-one cooler.
• Power supply form factor: most cases take ATX, small ones may need SFX.

Check the cooler lists your socket. A powerful processor needs a cooler to match: a slim low-profile cooler is fine for a modest chip and not enough for a high-end one. Many processors do not come with a cooler at all, so budget for one.

Add up what the processor and graphics card draw at full load, add some for everything else, and leave generous headroom. The graphics card maker publishes a recommended power supply wattage for each card, and it is a safe guide. The build planner sizes this for you.

• Check it has the connectors your graphics card needs: enough 8-pin PCIe cables, or a 12V-2x6 cable for many newer cards.
• Buy from a known brand. A cheap unit is the one part that can damage the others when it fails.

Use an M.2 NVMe SSD for the drive the operating system lives on. The board's manual lists how many M.2 slots it has and their speeds. Newer drives work in older slots, just at the older slot's speed, so a PCIe 5.0 drive in a PCIe 4.0 slot runs at 4.0 speed.

The PC builder only offers parts that match the socket and memory type of what you have already picked, and shows the estimated power draw and whether the graphics card fits the case. Every product page lists its full specifications. When the parts arrive, our build guide walks through putting them together.