You’ve done it! All the major components of your desktop PC are in place, and you’re just about ready to go. Have a final look through the case and check for any missed power or data cable connections among the major components.
Follow the leads off each fan (especially the CPU fan) and make sure they’re connected to the appropriate fan header on the motherboard. Make sure all cables are clear of the fans and you have all your front panel headers in
place. Once you’ve made sure everything is securely in place, go ahead and replace the side panels to your case and screw them in.
It’s time to plug it all in! Get your power cable connected to the PSU, your keyboard and mouse connected to either USB or PS/2 slots, and monitor connected to either the GPU (if you have one) or the motherboard. Turn the power
switch on the back of your PSU from Off (0) to On (1), and press the power button. If you’ve followed this guide and checked your work along the way you should see the BIOS splash screen after a couple moments and the system
will POST successfully.
Head into the BIOS and check your CPU temperature under “Hardware Monitor” or a similar name. Temperatures should be below 50C / 122F, but numbers slightly higher aren’t a call for panic. The temperature under the BIOS will be
higher because the CPU will be running at its base clock, which is higher than the “idle” downclock you’ll see once you’re inside your operating system. Check your temperatures once you’re set up and running and the system
is truly idling, not installing updates. You should be idling below 40C / 104F.
If this all checks out, congratulations, you’ve built a working custom desktop PC! From here, you’ll want to get your operating system (e.g. Windows, Linux, SteamOS, etc) installed. BIOS settings can be adjusted later to dial in
performance; it’s best to verify the system runs fine at its stock setup before you make changes that could negatively impact stability. Get your OS installed, set up your account and settings, and fetch all the drivers and
any updates you need. Most make the process pretty automatic and straightforward.