Into the case — study guide
The concept's fragments, read in order.
Two big parts go into the case
Your motherboard is not empty anymore. It already has its CPU and its RAM sticks locked into place, so it is ready for the next big step: going into the case.
In this part of the build, two parts move into the case. The motherboard goes in first, because everything else in your build will attach to it. The power supply goes in too, in its own spot, ready to eventually feed power to the whole machine.
By the end of this step, both parts will sit inside the case, held in with a few screws. Nothing will be plugged together yet, and the case will not power on. That part comes later. Right now, the job is simple: get the two big pieces settled into their homes.
Opening up the case
Before anything goes in, you need to get inside the case. Most cases have one or two side panels, flat covers on the sides, that come off to expose the empty space inside.
Some panels are held on with a few screws you turn by hand or with a screwdriver. Others use a latch or a clip, so you press a button or pull a lever and the panel pops free. A few open like a little door, swinging on a hinge. Whatever the method, it is meant to be gentle, since cases are not built to fight you.
Once the panel or panels are off, set them somewhere flat and safe, where they will not get scratched or stepped on. Now you can see the empty inside of the case: the metal tray where the motherboard will sit, and an open area nearby for the power supply. That is your workspace for the next few steps.
The tiny posts that hold the board
Look closely at the metal tray inside the case, and you will notice a few small raised posts sticking up, arranged in a pattern. These are called standoffs, and they matter more than their size suggests.
A motherboard is covered underneath with tiny metal solder points and circuits. If the board rested flat on the case's bare metal, some of those points would touch the case directly. Once the machine is powered on, that contact can cause a short, an unwanted electrical connection that can damage the board. Standoffs solve the problem by lifting the board just far enough off the metal that nothing touches like small feet or risers holding something up off a surface, so it never touches.
Standoffs are usually brass, and different cases handle them a little differently. In some cases, they come already in place, pushed into the tray at the factory. In others, you thread a few in yourself, matching them to the holes on your particular motherboard. Either way, before the board goes in, it is worth checking that a standoff sits under every hole the board will use, and nowhere else.
The back panel that matches the ports
Every motherboard has a row of ports along one edge, the spots where things like a keyboard or a monitor cable eventually plug in. The case needs a matching opening for those ports to poke through, and that opening gets its own piece: the I/O shield.
The I/O shield is a thin rectangular piece of metal with a pattern of cutouts punched into it, one for each port on your particular motherboard. It snaps into a rectangular opening at the back of the case, from the inside, before the motherboard goes anywhere near it. Try it, and it should click firmly into place, sitting flat against the case like a picture frame that has to match the exact shape of the picture it holds.
Installing the shield first, and the board second, is not just a suggestion, it is the order that works. Once the motherboard is mounted, there is no room left to wrestle a metal shield into place behind it. A couple of minutes spent lining up the shield now saves you from taking the whole board back out later.
Setting the board down and screwing it in
With the standoffs in place and the I/O shield snapped in, the motherboard is ready to go in. Lower it in at an angle, tilting the port edge toward the I/O shield first, so the ports line up with the shield's cutouts. Then lay the rest of the board down flat, resting it gently on the standoffs.
Look through each screw hole on the board. Underneath every one, there should be a standoff waiting. If a hole and a standoff do not line up, stop and check the board's position instead of forcing anything into place. Once everything lines up, add a screw into each hole, turning it by hand until it is snug.
Snug is the goal, not tight like closing a jar lid firmly, not straining to crush it. The screws only need to hold the board still; they are not straining against anything. A few gentle turns with a screwdriver after that is usually enough. If a screw fights you, back off and check that it is going in straight instead of pushing harder.
Finding the power supply's spot
The power supply is the box that will eventually turn wall power into the electricity your parts use. It gets its own space inside the case, usually a bay near the bottom, tucked below the motherboard, though a few cases put it up near the top instead.
The power supply has a fan on one side, and which way that fan faces matters. Many cases have a vent, often covered by a dust filter, right where the power supply sits. When that is true, the fan should usually face down, toward the vent, so it pulls in fresh air from outside the case. If a case has no vent under the power supply, the fan generally faces up into the case instead.
Slide the power supply into its bay so the back of it, the side with the power cord socket, lines up with the matching opening at the back of the case. It should sit flush, not tilted or hanging out. Once it is seated correctly, it is ready to be held in place.
Screwing the power supply in place
Once the power supply is seated in its bay, it needs to be held there so it cannot shift or rattle around. That job falls to a small set of screws driven in from the outside back panel of the case, right through the power supply's own mounting holes.
Line each screw up with its hole and turn it by hand first, the same snug-not-tight habit from mounting the board. Once all the screws are started, a few turns with a screwdriver finishes the job. The power supply should feel solid when you gently press on it, with no wobble and no give.
If a screw will not catch, do not force it. Check that the power supply is pushed all the way into the bay and that the holes are actually lined up. A misaligned power supply is a common, easy-to-fix mistake, and it is much easier to nudge into place now than after everything else is built around it.
Two parts down, ready for what's next
Step back and look at what is inside the case now: the motherboard, sitting firmly on its standoffs with its ports peeking through the I/O shield, and the power supply, screwed solidly into its bay. Two of the biggest, heaviest parts of the whole build are exactly where they belong.
This step matters more than it might seem. Every other part still to come, including the graphics card, the storage, and all the cables that will eventually connect everything, depends on the motherboard and the power supply already being mounted correctly. A board that is not seated right, or a power supply that is not secure, causes problems that are much harder to fix once the case is full.
Nothing is wired up yet, and the machine will not turn on today. That is fine. This step was never about power, only about placement. The next parts of the build will start connecting what is now sitting quietly, side by side, inside the case.