To check PCI slots in Windows 10 without opening your PC, open PowerShell and run Get-CimInstance Win32_SystemSlot | Select SlotDesignation, CurrentUsage. Each row is a slot on your motherboard. A CurrentUsage of 3 means the slot is available, and 4 means it’s in use. Because this information comes from your motherboard’s firmware, it isn’t always complete, so it’s worth confirming with your motherboard’s model and manual, or by looking inside the case.
Below are all the ways to check, from quick commands to finding exactly which card is in which slot.
Method 1: Check PCI slots with PowerShell
- Right-click Start and choose Windows PowerShell.
- Type this command and press Enter:
Get-CimInstance Win32_SystemSlot | Select SlotDesignation, CurrentUsage, MaxDataWidth - Read the results using the table below.
| Column | What it means |
|---|---|
| SlotDesignation | The slot’s name on the motherboard, like PCIEX16_1 (a full-length x16 slot) or PCIEX1_2 (a short x1 slot). The names match the labels printed on the board. |
| CurrentUsage | 3 = Available, 4 = In use, 2 = Unknown, 1 = Other |
| MaxDataWidth | A code for the slot’s maximum width. Many boards leave this blank or report it incorrectly. |
On older PCs, you can use Command Prompt instead: wmic path Win32_SystemSlot get SlotDesignation,CurrentUsage. Microsoft is phasing out WMIC, so PowerShell is the better choice.
Why results can be wrong: Windows only repeats what the motherboard’s BIOS reports. Some boards list slots that don’t physically exist, leave out M.2 slots, or show every slot as “In use.” If the results look odd, use Method 3.
Method 2: See which devices are using PCI Express
This shows what’s connected, even when the slot list is unreliable.
- Right-click Start and choose Device Manager.
- Click View > Devices by connection.
- Expand ACPI x64-based PC > Microsoft ACPI-Compliant System > PCI Express Root Complex.
- Each PCI Express Root Port or PCI Express Downstream Switch Port is a lane group. Expand them to see what’s attached, such as your graphics card, Wi-Fi card, or NVMe drive.
To see where a specific card sits, right-click it in Device Manager, choose Properties, and look at Location on the General tab. It shows something like PCI bus 1, device 0, function 0.
Method 3: Look up your motherboard model
Your motherboard’s manual lists every slot, its size, and its speed. This is the most accurate way to know what you have.
- Press Windows + R, type msinfo32, and press Enter.
- On the System Summary page, find BaseBoard Manufacturer and BaseBoard Product. That’s your motherboard’s brand and model.
- Search for the model on the manufacturer’s website and open the specifications or manual.
You can also get the model in PowerShell with Get-CimInstance Win32_BaseBoard | Select Manufacturer, Product.
On laptops and prebuilt PCs from brands like Dell, HP, or Lenovo, search for the computer’s model instead. Laptops usually have no standard PCI slots, only M.2 slots for storage and Wi-Fi.
Method 4: Use a free system information tool
Tools like HWiNFO and CPU-Z read your hardware directly and can show more detail than Windows.
- HWiNFO: Open it in Summary-only or full mode and expand Motherboard > System Slots to see each slot and whether it’s used.
- CPU-Z: The Mainboard tab shows your motherboard model and the graphics card’s current and maximum PCIe link width and speed, such as x16 and PCIe 4.0.
Download these only from the developers’ official websites.
Method 5: Check the slots physically
- Shut down the PC, switch off the power supply, and unplug it.
- Touch a metal part of the case to discharge static electricity.
- Remove the side panel and look at the motherboard below the CPU.
- Long slots are x16, the smallest are x1, and medium ones are x4 or x8. The slot name is printed next to each one.
A large graphics card often covers the slot below it, so a slot that’s “available” in Windows might not be usable.
PCI vs. PCI Express slots
| Slot | Typical use | Notes |
|---|---|---|
| PCIe x16 | Graphics cards | The top one usually has the full 16 lanes. Lower x16 slots are often wired as x4. |
| PCIe x1 | Wi-Fi, sound, USB, and network cards | Short slot. x1 cards also fit in larger PCIe slots. |
| M.2 | NVMe SSDs, some Wi-Fi cards | Uses PCIe lanes, but may not appear in the slot list. |
| Legacy PCI | Old expansion cards | Found mainly on older boards. Not compatible with PCIe cards. |
Frequently asked questions
How do I know if my PC has a free PCIe slot?
Run the PowerShell command in Method 1 and look for slots with a CurrentUsage of 3, then confirm by checking the motherboard or its manual.
How can I tell what PCIe version I have?
Look up your motherboard’s specifications, or check the Bus Interface field in GPU-Z or the link speed in CPU-Z. PCIe 3.0, 4.0, and 5.0 slots look identical.
Why does every slot show as “In use”?
Some motherboards report this incorrectly. Use Device Manager to see what’s actually connected, and check the board itself.
Does this work in Windows 11?
Yes. All of these methods work the same way in Windows 11.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.