For some, installing a CPU is one of the easiest parts of building a new PC. For others, it can be nerve-wracking, especially if they're doing it for the first time. While the basics of securing a CPU in the motherboard socket are fairly simple, there is potential for mistakes that can damage the processor or at least diminish performance. First-time builders or those assembling a PC after a long gap might commit these mistakes even if they try to be as cautious as possible. Sometimes, common myths or a missed detail can end up costing you hours of wasted time or, worse, a dead CPU.

5 Forcing it into the socket

The one thing you should never do

Controlling myself from making the mandatory Michael Scott phrase, I'll jump to why you should avoid doing this at all costs. CPUs are meant to fall right into place in the motherboard socket without the need for any manual force from you. Whether the pins are on the CPU (PGA socket) or the socket (LGA socket), you never need to maneuver the CPU in order to "make it fit."

In case you're facing resistance when inserting the CPU into the socket, check whether you have aligned it right. You can use the little triangle at the corner of the CPU and the socket for reference. If they're aligned, you're putting the CPU in the right way. Forcing the CPU into the socket will inevitably damage the pins on the CPU or the motherboard, potentially damaging either of them permanently.

4 Forgetting to lower the retention arm

It needs to go back to the way it was

Whether you're using an Intel or AMD motherboard, the CPU socket will have a metal retention arm or lever next to it, meant to firmly secure the CPU once it's in place. To install the CPU, you obviously need to release the retention arm to get access to the socket or the metal frame (LGA 1700 and AM5 motherboards). After inserting the CPU, however, you must not forget to return the retention arm to its original position.

Some users might assume that once the CPU is in the socket, it's fully "attached" to the motherboard. However, without the retention arm secured, the CPU might not make the necessary contact with the socket. This can lead to the CPU not receiving any power, the pins getting damaged due to movement within the socket, or the CPU falling out of the socket. Before you move on to the CPU cooler installation, double-check whether you've fully secured the CPU using the retention arm.

3 Forgetting the extra 4-pin power cable

Some CPUs won't boot without it

Usually, CPUs only need a single 8-pin power cable, and they're good to go. When you've assembled most of your new PC, you might be ready to plug in the huge 24-pin motherboard power cable, the 8-pin GPU PCIe cables, and the 8-pin CPU power cable, and call it a day. For some CPUs, however, you'll be greeted with a lifeless PC when you press the power button. Instead of wracking your brains about where you went wrong, you should check if your CPU requires an extra 4-pin power cable.

The 4-pin power connector is right next to the 8-pin connector, but it's easy to ignore it because most CPUs don't need the extra power. I've personally faced this problem when building a Ryzen 5 7600X PC on the ASRock B650 Pro RS WiFi motherboard — I skipped the extra 4-pin power cable like I always do, and ended up wasting hours trying to figure out the underlying issue.

The best way to avoid this mistake is to find out whether your CPU needs an extra 4-pin power cable beforehand. Alternatively, if your PC doesn't boot after the assembly process, this is the first thing you should check.

2 Applying too little thermal paste

It's better to apply too much paste instead

As a first-time builder, it's natural to be anxious about the amount of thermal paste you need to apply to your CPU before mounting the CPU cooler. To be honest, there's no right amount of thermal paste, just like there's no one right method to apply thermal paste. If I need to give you one piece of advice about thermal paste, it'll be to always apply more paste than you think, when in doubt.

This is because applying too little thermal paste is always worse than applying too much of it. The job of the thermal paste is to form a clean layer between the IHS of the CPU and the cooler heatsink for efficient thermal conduction. If you end up with too little thermal paste, your CPU will likely overheat due to insufficient contact with the CPU cooler. On the other hand, the extra thermal paste will just be pushed out toward the edges of the IHS, not interfering with efficient thermal conduction between the CPU and the cooler.

1 Forgetting a necessary BIOS update

Update the BIOS before removing the previous CPU

This one doesn't apply to every single build, but you should be aware of it, nonetheless. If you're upgrading to a new CPU on your existing motherboard, or even building a new PC with a CPU and motherboard not from the same generation, you might need a BIOS update for the board to recognize the CPU. As manufacturers launch new CPUs for existing sockets, as AMD does for AM4 and AM5, motherboards need to be flashed with a new BIOS to make the new chip work.

If you miss a mandatory BIOS update on your motherboard before building your brand-new PC, you'll start panicking when your machine doesn't boot. And, by the time you realize it, you'll need to remove the CPU cooler and the CPU, install a CPU that works with the motherboard (or your older CPU, if you're upgrading), flash the new BIOS, and then put the new CPU back in. Many motherboards have BIOS flashback, so this process doesn't need a compatible CPU — you can update the BIOS without disassembling the PC.

All this hassle can be avoided if you do your homework and figure out if the CPU you're using is already compatible with your current BIOS/UEFI version.

Installing a CPU is simple if you know your basics

As I mentioned before, installing a CPU is one of the simplest steps in building a PC, but if you're on your first build, it can be a bit overwhelming. You're dealing with expensive hardware and are afraid of breaking or damaging the components. You end up overthinking every little detail, and that can backfire sometimes. The answer is to do your homework before starting the build, consult some build tutorials from reliable publications, and avoid the most common mistakes.