Dell NVIDIA Mellanox CX4121C ConnectX-4 Lx MCX4121A-ACAT Dual Port SFP28 25GbE PCIe 3.0 x8 Network Interface Card (NIC) Ethernet Adapter 020NJD 20NJD

The Dell NVIDIA Mellanox ConnectX-4 Lx CX4121C Dual-Port 25GbE Ethernet Adapter is a high-performance enterprise-class Network Interface Card (NIC) designed for data centers, cloud infrastructure, virtualization, hyperconverged environments, software-defined storage, HPC clusters, and high-speed networking deployments. Featuring the proven NVIDIA Mellanox ConnectX-4 Lx EN (MT27710) controller, this adapter delivers ultra-low latency, high throughput, advanced hardware offloads, and exceptional reliability for modern enterprise workloads.

This Dell OEM adapter is sold under Dell part numbers 020NJD and 20NJD, and is equivalent to the Mellanox/NVIDIA retail model MCX4121A-ACAT with board model CX4121C.

---

Cross Reference Part Numbers

• Dell 020NJD
• Dell 20NJD
• Mellanox MCX4121A-ACAT
• Mellanox CX4121C
• NVIDIA ConnectX-4 Lx EN
• Mellanox MT27710
• Dell ConnectX-4 Lx Dual Port 25GbE Adapter
• Dell 0MRT0D MRT0D

---

Key Features

• NVIDIA Mellanox ConnectX-4 Lx EN Controller
• Mellanox Model CX4121C
• Equivalent to MCX4121A-ACAT
• Dell OEM Part Numbers 020NJD / 20NJD
• Dual-Port SFP28 Interface
• Supports 10GbE and 25GbE Ethernet
• PCI Express 3.0 x8 Host Interface
• Low Profile Half-Height Form Factor
• RDMA over Converged Ethernet (RoCE v1/v2)
• SR-IOV Virtualization Support
• VXLAN, NVGRE & GENEVE Offloads
• TCP / UDP Checksum Offload
• Large Send Offload (LSO)
• Large Receive Offload (LRO)
• Storage Acceleration Features
• Up to 512 Virtual Functions (VFs)
• VMware Ready
• Microsoft Hyper-V Compatible
• Proxmox Compatible
• Linux and Windows Server Compatible

---

Technical Specifications

General

• Manufacturer: Dell Technologies / NVIDIA Mellanox
• Device Type: Network Interface Card (NIC)
• Product Family: ConnectX-4 Lx
• Controller: Mellanox ConnectX-4 Lx EN
• ASIC: MT27710
• Board Model: CX4121C
• Equivalent Mellanox SKU: MCX4121A-ACAT
• Dell SKU: 020NJD / 20NJD

Interface

• PCI Express 3.0 x8
• Backward Compatible with PCIe 2.0
• Fits PCIe x8 and PCIe x16 Slots

Network Ports

• 2 × SFP28 Ports
• Dual-Port Ethernet Adapter

Supported Speeds

• 25GbE per Port
• 10GbE per Port
• Auto-Negotiation Support

Supported Media

• SFP28 SR Transceivers
• SFP28 LR Transceivers
• SFP+ 10GbE Modules
• Passive DAC Twinax Cables
• Active DAC Cables
• Active Optical Cables (AOC)

Power

• Typical Power Consumption: 9.3W
• Maximum Power Consumption: 11.1W
• Port Power Budget: Up to 1.5W per SFP28 Port

Environmental

• Operating Temperature: 0°C to 55°C
• Enterprise Data Center Rated

Form Factor

• Low Profile (LP)
• Half Height PCIe Card
• HHHL Design

---

Advanced Networking Features

RDMA & Low Latency

• RoCE v1 Support
• RoCE v2 Support
• Direct Memory Access Acceleration
• Ultra-Low Latency Networking
• High-Performance Computing Ready

Virtualization Acceleration

• SR-IOV
• Up to 512 Virtual Functions
• Hypervisor Offload
• Virtual Machine Direct I/O

Overlay Network Offloads

• VXLAN Acceleration
• NVGRE Acceleration
• GENEVE Acceleration

Stateless Offloads

• TCP Checksum Offload
• UDP Checksum Offload
• IPv4 Offloads
• IPv6 Offloads
• LSO
• LRO

Storage Offloads

• Erasure Coding Offload
• T10-DIF Validation
• NVMe-oF Networking
• Storage Traffic Acceleration

---

Dell Server Compatibility

PowerEdge 13G

• R630
• R730
• R730xd
• R830
• R930

PowerEdge 14G

• R240
• R340
• R440
• R540
• R640
• R740
• R740xd
• R740xd2
• R840
• R940
• R940xa
• T640
• C4140
• C6320
• C6420

PowerEdge 15G

• R450
• R550
• R650
• R750
• R750xa
• C6520
• C6525

PowerEdge 16G

• R660
• R6615
• R7615
• R760
• R7625

---

HPE Compatibility

ProLiant Gen9

• DL160
• DL180
• DL360
• DL380
• DL560
• DL580

ProLiant Gen10 / Gen10 Plus

• DL160
• DL180
• DL360
• DL380
• DL560

ProLiant Gen11

• DL320
• DL325
• DL360
• DL365
• DL380
• DL385

Apollo Series

• Apollo 2000
• Apollo 4200
• Apollo 4500

---

Lenovo ThinkSystem Compatibility

• SR530
• SR550
• SR570
• SR590
• SR630
• SR650
• SR850
• SR860
• SR630 V2
• SR650 V2
• SR630 V3
• SR650 V3

---

Cisco UCS Compatibility

• UCS C220 M5
• UCS C240 M5
• UCS C220 M6
• UCS C240 M6

---

Supermicro Compatibility

Server Platforms

• SYS-2029BT
• SYS-6029TP
• SYS-6019U
• SSG-6049P
• SYS-221BT
• Ultra SuperServer Series

Motherboard Families

• X10 Series
• X11 Series
• X12 Series
• X13 Series
• H12 Series
• H13 Series

Examples:

• X11DPH-i
• X12SPL-F
• X13SEI

---

Fujitsu Compatibility

PRIMERGY

• RX2530 M5
• RX2540 M5
• RX2530 M6
• RX2540 M6
• CX2550 M5
• CX2560 M6

---

ASUS Server Compatibility

RS Series

• RS700-E9
• RS700-E10-RS12U
• RS720-E9
• RS720-E10-RS24U

GPU Servers

• ESC4000-E10
• ESC8000-E10

---

Workstation Compatibility

Dell Precision

• Precision 5820
• Precision 7820
• Precision 7920
• Precision 7960

AMD Threadripper Workstations

• ASUS Pro WS WRX80E-SAGE SE

Intel Workstations

• ASUS Prime Z790-A
• ASRock Rack X570D4U
• ASRock Rack B550D4U
• ASRock Rack ROMED8
• Gigabyte X570 AORUS Series
• MSI B650 Tomahawk Series

---

NAS & Storage Platform Compatibility

Synology

• RS3621xs+
• RS4021xs+
• FS3410
• FS6400
• SA3400D

QNAP

• TS-h2490FU
• TS-h1290FX
• TDS-h2489FU
• TS-h3087XU

TrueNAS / iXsystems

• TrueNAS SCALE
• TrueNAS Core
• X-Series
• R-Series
• Mini XL+

Storage Software

• VMware vSAN
• Ceph
• GlusterFS
• NVMe-over-Fabrics
• Microsoft Storage Spaces Direct

---

Operating System Compatibility

Microsoft Windows

• Windows Server 2016
• Windows Server 2019
• Windows Server 2022
• Windows Server 2025

Linux

• Red Hat Enterprise Linux
• CentOS
• Ubuntu Server
• Debian
• SUSE Linux Enterprise Server

Virtualization Platforms

• VMware ESXi 6.5
• VMware ESXi 6.7
• VMware ESXi 7.x
• VMware ESXi 8.x
• Microsoft Hyper-V
• Proxmox VE
• Citrix Hypervisor
• XenServer
• KVM

---

Ideal Applications

• Enterprise Data Centers
• Cloud Infrastructure
• Hyper-Converged Infrastructure
• VMware Clusters
• Proxmox Clusters
• Hyper-V Environments
• Ceph Storage Networks
• vSAN Networks
• AI & Machine Learning Systems
• High-Performance Computing (HPC)
• Database Clusters
• Backup Servers
• Disaster Recovery Sites
• Video Production Networks
• High-Speed NAS Deployments
• NVMe-over-Fabrics Storage Networks
• Software Defined Storage (SDS)