Published On: Sep 16, 2019
In this step-by-step PSU installation guide for beginners, we'll explain how to install a power supply into a desktop computer case in an easy-to-understand way without the confusing tech jargon or advanced lingo. This tutorial applies to all types of ATX power supplies, whether you want to know how to install a modular PSU, semi-modular PSU, or non-modular PSU (we'll explain any things to know or nuances of either type as we go along).
Installing a power supply into your PC is simple, and shouldn't take you long even if you're completely new and building your first computer. It's just a matter of positioning it the right way around for the best airflow, slotting it into your case, and securing it with the screws provided. If you're wanting to learn about the power connections instead, see our separate power supply cables guide (the next step to take after you learn how to physically install your power supply).
Note: This PSU installation guide is part of our full How to Assemble a PC tutorial. Refer there for all PC installation steps.
The first thing you want to do when installing a power supply is check for the presence of little rubber feet on the bottom of your computer case. This is assuming you're installing a PSU in the bottom of your case, which is how every modern case is designed these days. Top-mounted power supplies is a thing too, but a thing of the past.
Many cases have rubber feet to help reduce the effects of PSU vibration to lower noise. If your case does have rubber feet like our Cooler Master N200 does, they'll likely already be pre-installed, but if not then check if your case provided you with some and go ahead and install them as per your case manual instructions.
If your case doesn't have rubber feet, it's not the end of the world, but you could always buy some small self-adhesive rubber pads from your local stationary store if you wanted to (and especially if your power supply vibrates loudly once your new battlestation is fully operational).
If you are installing a modular power supply (one where you can choose which power cables to attach and which to leave in that PSU box), it might help if you attach the power cables that you'll need to your PSU before you physically mount it into the case. In some cases, it could be a little tricky for you to go in and attach the power cables later on after the PSU has been installed. But just ignore this if you can easily reach the power connectors on your modular PSU even after it's sitting in the bottom of your case.
Before physically mounting the power supply into your case, you want to first figure out the best orientation/positioning for the PSU installation. In other words, you can choose between installing the power supply with the intake fan facing upwards towards the inside of your case, or facing downwards through the vents on the bottom of your case (which most modern cases will have).
So, which is best? PSU intake fan up or down? It's a good question, and a topic of much debate as with most cases you have the choice of either orientation.
The difference in performance won't be huge as these days most decent modern PSUs are quite efficient (and the fan won't always be running), so in most builds where you have the choice of the PSU fan vs down, either option is going to be just fine (so don't stress too much over your decision!).
However, there are certain situations where you should favor installing the PSU fan either up or down for optimal airflow and cooling:
Just remember to only install the PSU with the fan facing down if your case has bottom vents, though most cases will. Also, if positioning the PSU fan down towards the bottom grill, make sure you maintain some sort of clearance between your case and the surface it's on so that the fan can suck in air properly (and not overheat/choke). Most cases will be raised enough by its feet though so you should be fine.
For the example PC build we're installing here in this tutorial using the Cooler Master N200, we will mount the power supply with the fan facing up because the user of this system will sit the machine on carpet.
Before installing a power supply into your PC, remember to ground yourself before physically handling your power supply or the inside of your case by either wearing an ESD wrist strap (see the tools you need to build a PC) or by regularly touching a metal object.
Now you know the right way to install your power supply, it's time to fit it in the bottom of your case, which is where most modern cases house the PSU as mentioned earlier. If you're installing a top-mounted power supply, the process is going to be very much the same as you just need to slot it in and screw it into the place like we'll be doing here for our bottom-mounted PSU installation.
If you have your case lying on its side from previous installation steps, to install your power supply unit you'll want to sit your case upright. Go ahead and place the power supply unit in the bottom of the case, making sure the power socket and power switch face out the rear of the case, with the cable connections facing into the case.
Line up the screw holes on the back of the case with the PSU, and while holding the PSU firmly in place go ahead and screw them in with the screws that should have been provided with your PSU. Otherwise, use screws provided by the case. Tighten them nice and firmly, but not overly tight.
Screw your new power supply in at each corner with a screwdriver
That's all there is to installing a power supply into the case. Now it's time to connect the cables to the rest of your build, including a little good old cable management.
PC Assembly Hub: How to Assemble a PC