If you're about to build a PC for the first time, you'd be forgiven for making some common mistakes that first-time builders are prone to. However, even those with a few builds under their belt can sometimes forget some obvious or unsaid things, making mistakes that can range from annoying to disastrous. These mistakes aren't always written about in articles about annoying PC mistakes, which is why many users are still guilty of them in 2025.

5 Forgetting the motherboard standoffs

It can happen to the best of us

If you've not assembled a PC in years, or are building one in a hurry, you might forget that the motherboard needs standoffs before you can secure it to the case. If your case doesn't already come with standoffs pre-installed, installing the motherboard without them can potentially lead to short circuits or damage to the motherboard's PCB. I did this once with an old motherboard and case around 9 years ago before I realized my mistake, and removed the motherboard to install the standoffs.

Sometimes, the pre-installed standoff might not align with the holes on your motherboard, in which case you'll need to remove some of the standoffs and adjust them accordingly. Also, when tightening the screws to the standoffs, don't go overboard. You should aim for a secure installation without excessive tightening to protect the motherboard's PCB from strain or breakage.

4 Waiting till the end to route cables

Planning ahead is more convenient

I know it's tempting to put off cable management till the very end, but the best time to plan how you'll route the major cables is halfway through the build. When you've secured the motherboard inside the case, and installed the CPU, RAM, and SSD, deciding how you'll route the cables for the CPU cooler, front panel, motherboard & CPU power, and the graphics card can eliminate a lot of hassle later on.

By planning ahead, you have a clearer picture of which holes and grommets will be used to route the cables, which points behind the motherboard will be used to tie them, and how you'll avoid the dreaded cable jungle. By doing this, you'll not only save time and avoid unnecessary frustration, but also save your cables from damage due to excessive force later on, when you're too frustrated and just want to get it over with.

3 Mounting the case fans in the wrong direction

Redoing multiple fans is a pain

I've been guilty of this one as well. When helping my brother build his new PC around two years ago, we had to install a total of 9 fans (including 3 for the AIO radiator). While we were clear on the fan configuration and the intake/exhaust setup, we somehow installed three side intake fans in the opposite direction. Instead of pulling air into the case, they were set to exhaust, which was, obviously, not the intention.

Needless to say, this led to a lot of blame being thrown around, and precious time being wasted on removing and reinstalling the fans in the correct orientation. Another potential mistake is installing the AIO or intake fans in the wrong order when daisy-chaining fans. Depending on the model of your case fans, you might have to see which of the three (or two) fans is the "master" fan or has extra cables or ports, so that cable management doesn't become tricky. Otherwise, you'll have to remove the fans when you realize the mistake, and waste time reinstalling them in the right order.

2 Installing the PSU upside down

You might be doing it wrong

The power supply has a built-in fan that draws air into the unit and exhausts it from the rear of the case to prevent overheating. Depending on your case and how much room the PSU fan has for exhaust, you'll have to decide how to install the power supply. Most cases have the PSU mount at the bottom with a vent for air intake. In such cases, the fan side of the PSU should be facing downwards, away from the case, so that it can draw cool air from the bottom and exhaust it from the rear.

For top-mounted power supplies, the idea is the same — drawing air from the side and exhausting it from the rear of the case. Things get tricky when your case doesn't have a bottom or side intake, or it's obstructed. In that case, it's better to install the PSU with the fan facing the interior of the PC, so that it can get access to some air — warm air is still better than no air from an intake that's too restricted. In cases where the intake lacks a mesh filter to block dust, it's again better to mount the unit with the fan facing the inside of the PC.

1 Skipping the box test or breadboarding

A simple tip that saves a lot of time

Breadboarding is the practice of assembling the core components of a PC and testing the build outside the case. In the event that it doesn't power up or runs into a failed boot, you can diagnose the issue easily, avoiding a full disassembly (in the worst case). This technique is a simple precaution that catches mistakes before you're too far into the build process. Although diagnosing issues with a fully-built PC isn't impossible, doing it outside the case is far more convenient.

While dead-on-arrival components are rare, breadboarding can help you rule out any such issues at your end. You don't need to put everything together, route the cables, and waste hours only to remove everything if something doesn't work the way it should. Plus, if you're using pre-owned parts and are unsure about whether they'll work, breadboarding is a must.

It's good to revise the basics

These mistakes might seem too obvious to many of you, but it doesn't hurt to remind oneself of the basics now and then. After all, it only takes one particularly bad instance to ruin a build. You might irreparably damage a component or waste hours of effort before realizing your mistake. Avoiding the mistakes on this list can prevent such situations while keeping you humble as a PC builder.