5 Methods on How to Tell If a PCIe Slot is Bad: Step-By-Step

There are many ways to figure out if your PCIe slot is bad or not, the easiest way is by testing the slot with different cards that fit. Doing this would give you insight into the probable cause and highlight if the issue lies with the slot or with the device. There are also plenty of other ways to check using internal tools and utilities.

If you have been experiencing some problems with your motherboard, particularly in regards to malfunctioning PCIe peripherals, you are probably here to learn how to tell if a PCIe slot is bad.

So as mentioned earlier, you can either check manually via the process of elimination or by using some of the built in tools and utilities found inside the operating system.

If you are going to proceed with the manual way by testing a slot with different cards, you will need to take extra care to avoid any damages.

Checking through the use of OS built-in utilities should be easy for most people and can provide a lot of insight as to what the problem might be and how to solve it. However, built-in utilities are sometimes none conclusive.

By far the best method is to have PCIe slot testing kit, however, that method can be a bit expensive.

How to Tell If a PCIe Slot Is Bad?

There are several ways to go about this and it all depend on the tools and utilities you have at your disposal.

If you notice a problem after a new card installation and are unsure as to whether the problem lies with the newly installed card or the slot it went into, then here are some methods that you can use to troubleshoot:

  1. Process of Elimination
  2. Visual Inspection
  3. Using the Device Manager
  4. Using the BIOS
  5. Using a PCIe Test Card

Also Read: How to Tell if Motherboard is Bad or Dead?

1. Process of Elimination – Manual Method –

Graphics Card
Image: Try inserting the card into different slots.

You can use the process of elimination to find out if your PCIe slot has a problem. This is a little straightforward but can be risky particularly if you are not used to opening up your PC.

Essentially, you will need to have at least two PCIe slots for this to work.

What you do is:

  1. Take the card that you know for sure works from the suspected faulty PCIe slot.
  2. Insert it into another PCIe slot.
  3. If the problem persists, then the issues lies with card.
  4. If the problem resolves and the card is operating fine, then the issues lies with the PCIe slot.

Alternative method: you will need two PCIe cards for this (ideally of the same size).

  1. Take one card and insert into a PCIe slot.
  2. If the card does not work, then unplug it and plug in a second PCIe card into the same slot.
  3. If the problem persists and if the second PCIe card ALSO does not work, then there are high chances that the fault lies with the PCIe slot.

You can also install an already working PCIe card into the slot you’re testing. If it fails, chances are that the slot is bad.

Make Sure You are Delivering Enough Power to the Card

This is particularly true if you have recently installed a graphics card and it does not work.

Most graphics cards require PCIe POWER connectors directly from the PSU. If the power is not provided, then the card will NOT operate. In this case the fault does NOT lie with the PCIe slot but with insufficient power.

graphics card connected
Make sure for GPU, you have provided sufficient power

Also Read: How Many PCIe Cables Do I Need?

Make Sure You Are Using the Right Slot for the Right Card

It should be noted here that you MUST use the appropriate card for a certain slot.

Every expansion card has a specific PCIe lane requirement. For instance, NVIDIA Graphics cards have a requirement of 16 lanes ideally, but they can work with 8 lanes as well.

If you were to install this card in a slot with only 4 lanes, then it will NOT work.

This is often an issue because sometimes, a full size x16 slot may only actually have 4 lanes going to it.

how to tell if pcie slot is bad w
Image: Gigabyte GA-P67A-UD3 motherboard slots configuration.

Note above that this motherboard has a second x16 slot but only offers 4 lanes. Hence if you put an NVIDIA graphics card here, will not work.

So here the problem would not lie with PCIe slot, but with incorrect usage of the slot for your GPU.

Also Read:

2. Good Old Visual Inspection

This method goes in hand with the previous method.

It goes without saying that you could always rely on your eyes as the first and the easiest measure to figure out if your PCIe slot is bad.

Since you are going to open up your PC for the above method anyways, it is worth it to look for signs of any visible damage to the slot or to the pins lining the slot.

Doing so you may also come across dust accumulated removing which can result in a quick fix for your bad PCIe slot.

You should also check if the PCIe card is securely inserted into the slot. Sometimes you have to give the expansion card a gentle push to align it with the pins inside the slot.

Also Read: How To Tell if CPU is Bad or Dead?

3. Using the Device Manager

Device Manager Main
Image: Device Manager main default view. If you have installed a device, look for it under the appropriate section to see if it is detected. For instance, for a WiFi Card, you will look for it under “Network Adapters” section.

If you are on Windows, using the Device Manager can be the quickest way to determine whether your computer has hardware problems particularly pertaining to drivers.

With Device Manager, you get access to the status of all the devices connected to the motherboard as well as their driver information.

From this information, you may be able to tell whether you have a bad PCIe Slot.

To get to the device manager:

  1. Click the Start Button
  2. Search for “Device Manager”, and click on the first result.

Alternatively, (in case if the search box does not detect Device Manager):

  1. Click the Start Button
  2. Search for “Control Panel”.
  3. On its main menu, select “Hardware and Sound”
  4. Then find “Devices and Printers”
  5. Under this you will find the selection for Device Manager.

Note, the Device Manager DOES NOT show the PCIe slots themselves! It shows only the ATTACHED devices. So if you have attached a particular device, say a network adapter, and if it does not show that could indicate a problem with the PCIe slot.

Also Read: Where is Motherboard in Device Manager?

Exclamation Mark in Device Manager

Exclamation Mark
Image Source: Intel

Sometimes you may find a device with an exclamation mark next to it. If you see this, it basically means that the PCIe slot is working fine, but the issue either lies with the installed device or its drivers.

4. Checking the BIOS

The BIOS (Basic Input Output System) is the first piece of software that runs every time you start a computer.

One of its many function is the POST (Power On Self Test). The POST function is in charge of ensuring every bit of hardware connected to the computer that’s necessary for operation is up and running before the system can load the OS.

The BIOS itself is also used to configure various hardware on the computer which can come in handy if you need to tell whether you have a bad PCIe slot.

Accessing the BIOS

You can use the BIOS utility before the computer boots into the OS. There are various key combinations to access it and they will depend on the motherboard.

Find the BIOS key for your computer, then restart the computer while pressing that key. Usually, this is the F2 or the DEL key on most computers.

The booting process will be interrupted and you will be taken to the BIOS utility.

Also Read: How to Reset BIOS?

Finding the PCIe Settings

This will depend on the BIOS version you are running. Nevertheless, you will likely find the settings for PCIe under the Advanced Settings tab.

You will need to check if all the PCIe slots are listed and also you need to ensure they are enabled. You will also need to check if the PCIe Bus is overclocked or not. If the PCIe Bus is overclocked than that can bring about a load of issues.

Sometimes the slot with a graphics card can be disabled if your motherboard comes with an integrated GPU. This may cause the installed GPU to fail and you may mistakenly think that the slot is bad.

It should be noted that not all BIOS version are comprehensive enough to allow control over the PCIe slot configuration thoroughly.

5. Using a PCIe Test Card

How to Tell If a PCIe Slot is Bad
Image: PCIe Slot Test Kit

This is a comprehensive solution for how to tell if a PCIe slot is bad. A PCIe test card offers basic features that allow you to test the performance of your slot and will even alert you of any present issues.

Some come with status LEDs that give you a glance at the slot’s various performance parameters as soon as you switch on the card.

Some products offer a comprehensive analysis kits to test your PCIe slots. These are great if you run a IT store.

How this Works:

PCIe slot test kit

Just like a regular expansion card, you insert this unit into the PCIe slot in question. The computer needs to be off for this and proper care should be taken.

Once installed, you switch on the computer, and the card will immediately be powered on and it start analyzing your slot.

In the end, the inserted card will give you visual indicators as well codes corresponding to certain issues with the slot.

Some come with software that you can install on your computer to let you run comprehensive tests against your PCIe slot. This is a great way to find problems with your slot.

Again, PCIe test kits can get quite expensive, therefore, they are more suited for those who run an IT store and who regularly work with fixing broken motherboards.

Also Read:

Final Words

PCIe slots can be tricky to diagnose, especially when something goes wrong and your installed devices start to malfunction.

Here I talked comprehensively about how to tell if a PCIe slot is bad, and there are different ways to go about it.

For me, the best and the most decisive method is to use the process of elimination whereby we would install a certain card in different slots, or perhaps even in different computers, to see if the issue lies with the slot or with the card.

The methods that uses built-in tools like BIOS or the Device Manager are a bit non-intrusive, but they can be inconclusive.

Of course, the holy grail for knowing if your slot is bad or not is to get the PCIe Test Kit. However, an investment in this kit is only justifiable if you run an IT repair store.

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Atif Qazi
Atif Qazi is the founder of PCGuide101 and an expert in the computer peripheral industry with over two decades of experience. He has worked as a consultant for major companies and has a deep understanding of the inner workings of computer peripherals. He has a degree in Electrical Engineering and has served as a product manager and technical consultant. He is passionate about testing and evaluating the latest products to provide readers with reliable information.

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