installed PCIe x8 network adapter into a PCIe x16 downsized to x4 and it is not recognized

[joseoh]

installed PCIe x8 network adapter into a PCIe x16 downsized to x4 and it is not recognized

[VikramTheGreat]

Hi @joseoh,

Welcome to the HP Support Community.
 

Thank you for posting your query. I will be glad to help you.

I understand that after installing a PCIe x8 network adapter into a PCIe x16 slot (running electrically at x4) on your HP Desktop, the system is not recognizing the card. I’ll guide you through the correct checks and steps to help resolve this issue.

Step 1: Verify physical installation

1. Power off the desktop and unplug the power cable.
2. Remove the side cover and reseat the network adapter. Carefully ensure it is fully and evenly inserted into the PCIe slot.
3. Confirm that no metal part of the bracket or PCB is touching other components.
4. If your motherboard has multiple PCIe slots, try installing the card in another full-length slot if available.

Step 2: Confirm slot configuration in BIOS

1. Power on the PC and repeatedly tap F10 to enter the BIOS Setup.
2. Under Advanced → PCI Devices Configuration (menu names may vary), check:
   • Whether the slot is enabled.
   • The PCIe link speed and lane configuration (set to Auto or Gen3/Gen4 depending on card support).
3. Save changes and restart the system.

💡 Some HP BIOS versions allow disabling or reserving PCIe slots; make sure the one you’re using is active.

Step 3: Verify detection in Device Manager

1. Boot into Windows.
2. Open Device Manager → expand Network adapters or Other devices.
   • If the card appears with a yellow mark, right-click → Update driver → Search automatically.
   • If it doesn’t appear at all, go to View → Show hidden devices.

If still not listed, proceed to the next step.

Step 4: Check with HP Hardware Diagnostics

1. Power off the PC.
2. Power it back on and repeatedly tap F2 to enter HP PC Hardware Diagnostics (UEFI).
3. Go to Component Tests → PCIe Device Test to verify if the system hardware detects the adapter.
   • If the adapter is not detected here, it’s likely a compatibility or slot issue.

Step 5: Compatibility notes

• Some HP desktop motherboards only support specific PCIe lane configurations or BIOS whitelists for certain card types.
• Ensure the network card is UEFI compatible (not legacy-only).
• If possible, test the adapter in another PC to confirm it’s functioning correctly.

I hope this helps.

Take care and have an amazing day!
 

Did we resolve the issue? If yes, please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!

Regards,

VikramTheGreat

[VikramTheGreat]

Hi @joseoh,

Please try the steps shared and let me know if this helps.

Take care and have an amazing day!
 

Did we resolve the issue? If yes, please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!

Regards,

VikramTheGreat