NVIDIA ConnectX-4 Lx Ethernet Adapter Cards for OCP Spec 2.0 User Manual

The network ports of the ConnectX®-4 Lx adapter card for OCP Spec 2.0 are compliant with the IEEE 802.3 Ethernet standards listed in Features and Benefits. Ethernet traffic is transmitted through the SFP28/QSFP28 connectors on the adapter card.


The adapter card includes special circuits to protect from ESD shocks to the card/server when plugging copper cables.

The ConnectX®-4 adapter card supports PCI Express Gen 3.0 (1.1 and 2.0 compatible) through an x8 or x16 edge connector. The device can be either a master initiating the PCI Express bus operations, or asubordinateresponding to PCI bus operations. The following lists PCIe interface features:

Supported PCIe Interface


PCIe Gen 3.0 (1.1 and 2.0 compatible) through x8/x16 edge connectors

Link Rates: 2.5. 5.0 or 8.0GT/s.
Auto Negotiation to: x16, x8, x4, x2 or x1.
Support for MSI/MSI-X mechanisms.


Applies to MCX4431M-GCAN

FRU EEPROM allows the baseboard to identify different types of Mezzanine cards. MEZZ FRU EEPROM is accessible through MEZZ_SMCLK and MEZZ_SMDATA (Connector A18 and A19). MEZZ FRU EEPROM address is 0xA2 and its capacity is 128Kb.

There are two, LED0 and LED1, and speed. LED0 is bi-color (yellow and green) LED and LED1 is a single color (green) LED. I/O LEDs per port to indicate link status.

Link Indications

LED and State


1Hz blinking Yellow

Beacon command for locating the adapter card

4Hz blinking Yellow

Indicates an error with the link. The error can be one of the following:

Error Type


LED Behavior


I2C access to the networking ports fails

Blinks until the error is fixed


Over-current condition of the networking ports

Blinks until the error is fixed

LED0 -
Link Speed

  • A constant Green indicates a link with the maximum networking speed.

  • A constant Yellow indicates a link with less than the maximum networking speed

  • If LED0 is off, then the link has not been established.

LED1 -

  • A blinking Green indicates a valid link with data transfer.

  • If LED1 is off, then there is no activity

A heatsink is attached to the ConnectX-4 Lx IC in order to dissipate the heat from the ConnectX-4 Lx IC. It is attached either by using four spring-loaded push pins that insert into four mounting holes or by screws.

ConnectX-4 Lx IC has a thermal shutdown safety mechanism that automatically shuts down the ConnectX-4 Lx card in cases of a high-temperature event, improper thermal coupling, or heatsink removal.

ConnectX-4 Lx technology maintains support for manageability through a BMC. ConnectX-4 Lx PCIe stand-up adapter can be connected to a BMC using MCTP over SMBus or MCTP over PCIe protocols as if it is a standard NVIDIA PCIe stand-up adapter. For configuring the adapter for the specific manageability solution in use by the server, please contact NVIDIA Support.

The voltage regulator power is derived from the PCI Express edge connector 12V supply pins. These voltage supply pins feed onboard regulators that provide the necessary power to the various components on the card.

© Copyright 2023, NVIDIA. Last updated on May 22, 2023.