This guide is part of a series covering how to identify and resolve issues while building or using your PC.  To get started, please check out the guide linked below:

NZXT Support - How to Identify and Read Debug Codes

In this guide, we will be covering what to do when you've identified a CPU issue with your PC.  This issue can be one of the more frustrating issues to deal with, however it can be easily isolated quickly compared to others.  CPU issues will usually come down to one of three factors:

• CPU + Motherboard Incompatibility
• Insufficient Power
• Socket Issues (Improper Mounting or bent/damaged pins)

Confirming your CPU is Compatible

An often overlooked step during the troubleshooting process, it is good to keep in mind that some motherboards may not only offer multi-generation hardware support but in some cases a CPU manufacturer may also have a few different revisions or staggered releases within a single generation.  For example, many motherboards in the Intel Z690 Chipset used in the NZXT N7 Z690 released with support for 12th generation processors exclusively but eventually gained support for 13th generation processors through UEFI/BIOS updates.  Conversely, the AMD B550 Chipset used in the NZXT N7 B550 released with support for Ryzen 3000 and 5000 processors but required a BIOS update to support the later released Ryzen 7 5800X3D.

Socket Compatibility

LGA 1700 vs. LGA 1200 Comparison, Image credit: VideoCardz

When confirming if your motherboard is compatible with your CPU, it's best to start by checking the socket for the motherboard.  In most cases, so long as the socket is the same the processor will likely be compatible with only a few exceptions.

For example, taking a look at the NZXT N7 Z690 Motherboard we can see that this motherboard uses the LGA 1700 socket used by the Intel 12th, 13th, and 14th generation processors.  This motherboard is compatible with all three of these generations, however on boot you may get a CPU Debug LED when trying to boot with a 13th or 14th generation processor.  For these processors, a UEFI update may be necessary in order to unlock full compatibility with these newer chips.

BIOS Compatibility

With socket compatibility confirmed, the next thing that should be checked is that the UEFI (also known as the BIOS) is going to be compatible with the processor in question.  The UEFI is the underlying code that allows the hardware in the computer to communicate across the motherboard.  A major upside to having an updatable UEFI on a motherboard is that later updates can enable support for products that did not exist when the motherboard was initially released such as newer processors.

Depending on the motherboard manufacturer, you may be able to check the version of the UEFI that was installed at the factory through a sticker placed somewhere on the board itself.  For example, all NZXT N7 Motherboards starting with the N7 Z490 (Intel) and N7 B550 (AMD) will include a sticker in the top-left corner of the motherboard near the I/O plate.  This sticker will have the exact BIOS revision that shipped on the motherboard from the factory.

If your motherboard lacks a version sticker or any other identifier, the best practice is to assume that the motherboard has never had its UEFI updated and is running the initial release version.  You may also be able to check the product page for the motherboard to see if there is a CPU Support List provided, as this will break down the BIOS revision necessary for your particular processor.

How do I update my BIOS if my PC cannot start?

Depending on your motherboard, you may have a feature that allows you to update the UEFI without needing to boot the PC.  This feature is commonly known as BIOS Flashback or BIOS Flash Mode and is made to help troubleshoot and resolve issues that may come up due to an outdated or corrupted UEFI.  This feature will vary from motherboard to motherboard, so it is recommended to check your motherboard user's manual for further information.

Checking for CPU Power Issues

Depending on the model of your processor, your system may need some additional power in order to start up and power the processor.  This additional power is usually routed to the socket through a 12V CPU Power connector located not far from the CPU socket (with most motherboards, this will be in the top-left corner of the motherboard).

If this connection is not present or is loose, this can result in issues where the PC is not able to properly power on or may give you a CPU Debug LED.  For most motherboards, this will be an 8-pin power cable with some enthusiast boards including an additional 4 or 8-pin connection.  Make sure that the cable connected to this port is securely connected and locked in, as this is crucial to the CPU itself.

Checking your CPU & Socket

Once everything else has been checked, the last thing to confirm is that there is no issues with the socket or the CPU itself.  This process will be different based on your CPU, specifically if it is either a Land Grid Array (LGA) CPU or if it is a Pin Grid Array (PGA) CPU.

An AMD AM4 Socket (PGA) compared to an Intel LGA 1700 Socket.

Land Grid Array or LGA is a socket type where the CPU will feature contact pads along the bottom of the CPU and will have an array of pins inside of the socket on the motherboard that make contact with these pads.  Most Intel CPUs will be LGA, as well as newer AMD Ryzen series chips starting with the Ryzen 7000 series.

Pin Grid Array or PGA is the opposite of LGA in that the pins are instead located on the underside of the CPU and the CPU socket includes an array of holes that the CPU pins physically socket into  Most AMD Ryzen CPUs from the Ryzen 5000 series and older will be PGA.

Checking LGA CPUs and Sockets

If you have an LGA CPU and Motherboard, start by checking the underside of the CPU to confirm that there is no debris, dust, or other contaminants on the CPU itself.  If there is any debris or contaminants such as thermal paste, this can be easily cleaned off by gently wiping the surface using a paper towel soaked in a small amount of isopropyl alcohol.

Do not use a cloth or microfiber cloth, as these may have small loops that can catch onto the pads or surface mounted components and damage the processor.

Example of bent pins on an LGA Socket, Image credit: reddit u/Wanheda_007

For the socket, check for any bent pints or debris.  For debris in the socket, it's recommended to blow this out using compressed air.  Please do not touch the pins directly in order to clear debris under any circumstances.  The pins in an LGA socket are very delicate and can be bent or broken if touched directly.  If you notice any bent pins in the socket itself, it is recommended to replace the motherboard as a whole or reach out to the motherboard manufacturer for further assistance.

Checking PGA CPUs and Sockets

If you have a PGA CPU and Motherboard, start by checking the underside of the CPU to confirm that there is no debris, dust, or contaminants on the CPU.  If you notice any debris or contaminants, it is best to try and blow it away using compressed air first.  For thermal paste, you can soak the underside of the CPU in isopropyl alcohol for 30-60 seconds before using compressed air to blow away the remains.

Another thing to look for on a PGA CPU is the presence of any broken or bent pins.  IF any pins are bent or missing, you may need a replacement CPU in order to resolve the issue.  For pins that are lightly bent, an experienced builder may be able to straighten the pins out with little effort.

Example of bent pins on a PGA CPU, Image credit: iFixit

For the socket, check for any debris in the socket holes.  Most debris will be surface level and can be easily blown away with compressed air or wiped off using an alcohol wipe.  For any debris stuck in a socket hole, we do not recommend attempting to clean the socket directly as this can damage the contacts within the holes.  For further assistance with PGA socket issues, pleas reach out to the motherboard's manufacturer.