by Adam Armstrong

Mellanox ConnectX-4 Lx Dual Port 25GbE DA/SFP NIC Review

Much like the recently reviewed Dell Mellanox ConnectX-4 Lx, today we will be looking at the traditional HHHL version of this NIC. The NIC is designed to add high bandwidth with low latency and a high message rate with its 25GbE transfer rate (though it is compatible with 10GbE as well). The NIC is ideal for next-generation web, Cloud, data analytics, database, and storage platform use cases.

The standard PCIe form factor also makes it compatible for Open Compute Project (OCP) also meeting the OCP Specification 2.0 and 0.5, as applicable. The NIC offers several key benefits including smart interconnect for x86, Power, ARM, and GPU-based compute and storage platforms, virtualization acceleration, power efficiency, Mellanox PeerDirect communication acceleration, and end-to-end QoS for congestion control.

Mellanox ConnectX-4 Lx specifications:

  • Device Type: Network Adaptor
  • Form Factor: HHHL x8
  • Interface: PCIe
  • Data Link Protocol: 25 Gigabit LAN
  • Data Transfer Rate: 25Gbps
  • Expansion / Connectivity
  • Interfaces: 2 x 25Gb Ethernet
  • Power
    • Voltage: 12V, 3.3V
    • Typical Power: 9.3W
    • Maximum Power: 11.1W
  • Temperature:
    • Operational: 0°C to 55°C
    • Non-operational: -40°C to 70°C
    • Humidity: 90% relative

Design and Build

The Mellanox ConnectX-4 Lx is low profile, dual Ethernet configuration, plug in network interface card. The NIC can easily be installed in an empty x8 PCIe slot. The front of the card has the two SFP+ ports and a black heat sink covering the Mellanox controller.

The other side of the card is more or less blank with identification stickers. Mellanox ships both full-height and half-height backplane adapters for broader compatibility.


The Mellanox ConnectX-4 Lx Dual Port 25GbE DA/SFP is a PCIe NIC that can be easily added to most servers that have an open slot. As with most Mellanox NICs, the ConnectX-4 Lx is all about high bandwidth, low latency, and high message rate. Though it has two 25GbE ports it is backward compatible with 10GbE for those that are looking to futureproof their network but have yet to upgrade. The NIC comes with several features aimed at improving performance as well as improving ROI while lower CAPEX and OPEX.

The Mellanox ConnectX-4 Lx NICs will be playing a key role in the StorageReview Lab over the coming months. We are migrating to a 25/50/100Gb networking fabric leveraging Dell's Z9100 100Gb switch, with primary server connectivity switching from our existing 10Gb fabric over to 25Gb across the board. These Mellanox NICs, available in different formats, will be the workhorse going forward across a wide variety of server platforms.

The Bottom Line

The Mellanox ConnectX-4 Lx Dual Port 25GbE DA/SFP NIC can easily be added to servers to bring them to a new level of network performance. 

Mellanox ConnectX-4 Lx Product page

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