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Resolution for DekTec Gen3 PCIe Cards Not Detected in Gen4/5 Slots PC servers may not detect DekTec PCIe Gen3 cards in Gen4/5 slots due to the DLFE feature. To resolve this issue, users should disable the DLFE function in the BIOS settings or use the “Data Link Feature Cap” setting. Detailed instructions are provided below.
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Affected DekTec Gen3 PCIe Cards
Systems Supporting DLFE Fix
The following systems have been successfully tested with the DLFE fix. Other systems may also be compatible, but have not been verified.
| ASRock WRX90 WS EVO |
| Asus Pro WS WRX90E-SAGE SE |
| Dell Poweredge R530 |
| HPE DL360 Gen11 |
| Intel M50CYP1UR204 Coyote Pass |
| Supermicro AS-1113S-WN10RT |
| Supermicro AS-4125GS-TNRT |
| Supermicro MBD-X13SEW-TF |
| Supermicro SSG-640P-E1CR24H |
| Supermicro X12SPI-TF |
| Supermicro X12SPL-F |
| Supermicro X12SPW-TF |
| Tyan S8050GM4NE-2T |
Problem Description
When a DekTec PCIe Gen3 card is used in a PCIe Gen4 or Gen5 slot with the Data Link Feature Exchange (DLFE) enabled, the card may fail to initialize. DLFE messages, introduced in the PCIe Gen4 PCIe specification, are not recognized by the PCIe Gen3 interface on the affected DekTec cards, causing them to stall. Consequently, the card is not detected by the operating system, and neither the Device Manager in Windows nor the 'lspci' tool in Linux will report its presence. In some instances, the PC may not boot at all, with the BIOS reporting a “PCI bus enumeration” error.
Resolution
To resolve this issue with the affected cards, users should:
- Access the BIOS settings and disable the DLFE function.
- If the DLFE option is not available, check for BIOS updates from the motherboard manufacturer.
- In some BIOS versions, enable the “Data Link Feature Cap” setting to make the DLFE option appear.
The PCIe Gen4 specification advises BIOS vendors to provide an option to disable the DLFE function in their BIOS settings, allowing Gen3 cards to boot normally. Disabling DLFE ensures the Gen3 cards can initialize properly without causing the system to stall.
Important Note
Disabling DLFE can lead to a performance penalty for true Gen4/5 cards. Therefore, if the BIOS permits disabling DLFE on a per-slot basis, it is recommended to disable DLFE only for the slot containing the DekTec card.
For any further questions regarding this issue, please contact DekTec.
