MCX512A-ACAT: NVIDIA ConnectX-5 EN Dual-Port 25GbE SFP28 PCIe 3.0 x8 Low-Profile Ethernet Network Adapter
Also listed as: ConnectX-5 EN 25GbE, MCX512A-ACAT-SP, MCX512A, MCX512A-ACUT · made by Mellanox
The NVIDIA (Mellanox) ConnectX-5 EN dual-port 25GbE SFP28 network interface card provides hardware-accelerated RoCEv2 RDMA, NVMe-oF target offload, and ASAP2 accelerated switching and packet forwarding. Connecting via PCIe 3.0 x8, it delivers sub-microsecond latency and up to 200 million packets per second for distributed cloud and high-performance computing clusters. Second-hand buyers should check mstflint firmware version, verify PSID strings if crossing between OEM and stock Mellanox cards, and inspect optical connector cages.
Specifications
| Part number | MCX512A-ACAT |
|---|---|
| Brand | NVIDIA |
| Made by | Mellanox |
| Type | Network adapters |
| Other numbers | ConnectX-5 EN 25GbE, MCX512A-ACAT-SP, MCX512A, MCX512A-ACUT |
| Status | current |
| Interface | PCIe 3.0 x8 |
| Form factor | PCIe Low Profile |
| Ports | 2x 25GbE SFP28 |
| Speed | 25GbE |
| Generation fit | PCIe Gen3 and Gen4 enterprise servers |
About the MCX512A-ACAT
MCX512A-ACAT is NVIDIA's (Mellanox) ConnectX-5 EN dual-port 25GbE SFP28 PCIe 3.0 x8 low-profile network interface card. Supporting hardware-accelerated RoCEv2 RDMA, NVMe-oF target offloads, and ASAP2 accelerated switching, it delivers sub-microsecond latency and up to 200 million packets per second for cloud virtualization, high-frequency trading, and distributed Ceph storage.
Compatibility
Installs into standard PCIe 3.0 and 4.0 x8 or x16 slots in enterprise servers from Dell, HPE, Lenovo, and Supermicro. Features dual SFP28 ports supporting 25GbE and 10GbE optical transceivers or DAC cables. Supported in Linux by the native mlx5_core driver and MLNX_OFED software stack. Low-profile and full-height brackets are supported.
How to identify a genuine unit
A genuine card displays a green PCB with an official Mellanox/NVIDIA serialized label showing model MCX512A-ACAT and Board ID MT_0000000009. In Linux, lspci detects Mellanox Technologies MT27800 Family [ConnectX-5]. Official firmware updates apply cleanly via mstflint.
Buying used
Query mlxconfig or mstflint to verify PSID and firmware revision. OEM-branded versions (such as Dell or Lenovo FRU units) can be cross-flashed to standard Mellanox stock firmware if desired. Inspect SFP28 cages for bent pins and confirm both ports negotiate 25G speed.
Reference prices (last 14 days, updated 2026-10-27)
New: USD 275 (1 sighting, Oct 2026)
Used: USD 145 (1 sighting, Oct 2026)
All sightings
| Seller | Condition | Price | Note | Seen |
|---|---|---|---|---|
| serversupply.com | new | USD 275 | 2026-10-27 | |
| ebay.com | used | USD 145 | 2026-10-27 |
Prices seen on public listings on the dates shown, before tax and shipping. Not an offer.
Fits these models
Equivalent part numbers
- Lenovo 4XC7A08633 ThinkSystem Mellanox ConnectX-5 EN 10/25GbE SFP28 2-Port PCIe Ethernet Adapter
- Dell 540-BBUK Dell Mellanox ConnectX-5 Dual Port 25GbE SFP28 PCIe Adapter
FAQ
What driver does ConnectX-5 use in Linux?
The in-kernel mlx5_core driver and MLNX_OFED enterprise software stack.
Does MCX512A-ACAT support 10GbE optics?
Yes, it auto-negotiates seamlessly with 10GbE SFP+ transceivers and DAC cables.
Buying or selling MCX512A-ACAT?
New, refurbished or used. Tell us the quantity and condition and we connect you with a vetted reseller in your region, usually within one working day.
Sources
- NVIDIA ConnectX-5 EN Ethernet Adapter Cards User Manual, checked 2026-10-27