Build in the right order.

Note the maximum graphics card length, the maximum CPU cooler height and the power supply form factor the case accepts. Use the manufacturer's figures for the exact revision you own, not a forum memory, and enter them on the Clearance sheet.

Card length, cooler height and PSU form factor come from each part's own data sheet. If a figure is missing, wait or measure a sample. A guess in a small case is how returns happen.

Fill in the rated draw for the processor and graphics card first, then everything else. Keep a headroom figure you can defend, and note which power supply form factor the suggested wattage has to come in.

Count the board power, processor power, graphics power and drive connectors, and compare with what the supply provides. In a small case, an unused modular cable is a cable you never have to hide.

Place the power supply, graphics card and cooler or radiator in the bare case without screws. If anything fights you now it will fight harder later, and this is the cheapest moment to change your mind.

Take off side panels and dust filters, and pull out drive cages or trays you will not need, to open up working room. Sort screws by type in a small tray; compact cases tend to use several lengths.

Choose which fans pull air in and which push it out, and mount fans or a radiator first when they would block access later. Note the airflow arrow on each fan so none goes in backwards.

Match the corner marker, lower the chip straight down and close the retention without force. Never press a chip into a socket; if it does not drop in, it is misaligned.

Open the clips, align the notch and press until both clips snap. If you are not filling every slot, use the ones your board manual lists first.

A drive slot hidden under a graphics card or cooler is miserable to reach once the board is mounted. Fit the drive and any heatsink or thermal pad now.

Some coolers must go on before the board is in the case, others after. Check the cooler's instructions against your case: a tall tower may block panel removal, and a low-profile unit may need the board out of its tray.

In many compact cases the supply occupies space the board needs for access. Install it, route its cables toward where they will end up, and leave them loose.

Confirm every standoff position your board uses is filled and that no extra standoff sits under bare circuit board. Fit the rear I/O shield first if it is a separate piece.

Small connectors vanish once a card or cooler is in. Wire the power switch, LEDs, USB and audio headers now, using the pin map in the board manual.

Mount any drives, then connect data and power on the shortest route you can see. Avoid draping cables across a fan path.

Use the processor fan header for the CPU cooler and group case fans on system fan headers. Check the board manual so pumps and fans get the intended signal.

A flexible riser needs gentle bends and a firm seat at both ends. Fit and secure it before the card so you can check both connections by eye.

Align the slot, press until the latch clicks and fix the bracket with screws. Do not leave a heavy card held only by the slot.

Use the connector type and count your card specifies. Do not swap modular cables between different supplies, because pin layouts can differ even where the plug fits.

Bundle slack where it cannot touch blades and keep cables out of the cooler's intake path. Use gentle bends; a tight bend stresses a connector.

Press each power and data connector until it clicks or stops. The main board connector, the processor power and the graphics power are the ones most often left half-seated.

Boot with a monitor on the graphics card output. If it does not start, check the seating of memory, processor power and graphics power before anything else.

Enable your memory profile if the memory supports one, set fan behaviour, and confirm the system sees every drive and the full memory capacity.

Install from a freshly prepared installer, then add chipset and graphics drivers from the component makers' own downloads.

Run a long, demanding workload while monitoring temperatures and fan noise, and compare readings with the limits the component makers publish. Small cases heat-soak slowly, so test for longer than a few minutes.

Panels change airflow. Refit them, repeat the load test and compare. If temperatures climb noticeably, revisit fan direction and cable position.