How to build your own PC

The five things that must match

Choose in this order, and each choice narrows the next:

• The processor decides the socket. The motherboard must have exactly that socket — there is no in-between.
• The motherboard decides the memory generation, DDR4 or DDR5, and how many modules there is room for.
• The case decides how long a graphics card and how tall a cooler will fit. Measure, rather than hope.
• The power supply has to handle the graphics card with headroom. The manufacturer states a recommended wattage — follow it.
• The motherboard also decides the number of M.2 slots for SSDs. Two is nice, one is enough for most people.

The order of assembly

Fit the processor, memory and M.2 drive to the motherboard while it is lying on the table. There is far more room there than down in the case, and this is the mistake people most often regret.

Then the motherboard goes into the case, then the power supply, and the graphics card last. Route the cables behind the tray while there is still room for your hands.

The classic mistakes

Four things are behind almost every machine that will not start the first time:

• The extra 8-pin CPU power connector at the top of the board is not plugged in. The machine is completely dead.
• Memory is in the wrong slots. The manual says which two to use when you only have two modules.
• The monitor is plugged into the motherboard output instead of the graphics card. The screen is black even though everything works.
• The standoffs between case and motherboard are missing or misplaced. That shorts the board against the tray.

First boot

Go into the BIOS first. Check that the processor, all the memory and the drive are there, and switch on XMP or EXPO so the memory runs at the speed you paid for. Then install Windows from a USB stick.