NVIDIA Mellanox® MCX515A-CCAT ConnectX-5 EN 100GbE Single-Port QSFP28 NIC

Identity
The NVIDIA Mellanox® MCX515A-CCAT is a single-port ConnectX-5 EN network adapter for 100GbE Ethernet. The QSFP28 port runs at up to 100Gb/s on a PCIe 3.0 x16 host interface. This is an Ethernet-only adapter — it does not support InfiniBand operation, even though some ConnectX-5 SKUs in the wider family are VPI (dual-protocol). New, factory-sealed unit. NVIDIA P/N: 900-9X5AD-0016-ST1.

Engineering Detail
PCIe 3.0 x16 provides ~128 Gb/s of effective host bandwidth — sufficient to fully saturate the single 100GbE port at line rate. The ConnectX-5 ASIC delivers approximately 750 ns end-to-end latency and up to 148 million messages per second (Mpps). Driver support via NVIDIA MLNX_OFED, in-box mlx5_core (upstream Linux), WinOF-2 (Windows), or nmlx5 (VMware ESXi).

What This Is NOT

Not a Multi-Host adapter. The "A" suffix on MCX515A-CCAT denotes the standard adapter card. Multi-Host SKUs in the ConnectX-5 family typically carry the "M" in the model number (e.g., MCX515M-...). Do not deploy this card expecting Multi-Host capability.
Not VPI / dual-protocol. This is the "EN" (Ethernet) variant. For dual-mode Ethernet/InfiniBand operation use the VPI SKU family (MCX556A-...).
Not a dual-port card. Single-port QSFP28 only.
Not 200G or 400G capable. Max 100GbE. For 200GbE use ConnectX-6, for 400GbE use ConnectX-6 Dx or newer.
Not bundled with QSFP28 transceivers, DAC cables, or low-profile bracket.


Capabilities

RDMA over Converged Ethernet (RoCE v1/v2).
NVMe over Fabrics (NVMe-oF) hardware offload — initiator and target.
ASAP² (Accelerated Switching and Packet Processing) for Open vSwitch offload.
Encapsulation/decapsulation acceleration: VXLAN, NVGRE, Geneve.
T10-DIF storage data-integrity offload.
SR-IOV virtualization (up to 1K virtual functions).
750 ns latency, up to 148 Mpps message rate.


Compatibility & Constraints

Switches: NVIDIA Spectrum / Spectrum-2 100GbE switching infrastructure.
Cabling: 100GbE QSFP28 DAC, AOC, SR4, LR4. Backward compatible with 10/25/40/50 GbE.
Drivers: MLNX_OFED, mlx5_core, WinOF-2, nmlx5 (versions matching firmware 16.x).
Slot: PCIe 3.0 x16 required for line-rate 100Gb/s. Gen3 x8 throttles to ~64 Gb/s.
Bracket: tall bracket only.


Specifications

OEM: NVIDIA Mellanox
Part Number (MPN): MCX515A-CCAT
NVIDIA P/N: 900-9X5AD-0016-ST1
ASIC: ConnectX-5 EN
Ports: 1 × QSFP28
Per-port speed: 100 GbE Ethernet (single protocol)
Host interface: PCIe 3.0 x16 (8 GT/s per lane)
Latency: ~750 ns
Message rate: up to 148 Mpps
Typical power: ~13 W
Standards: IEEE 802.3bj, IEEE 802.3by, RoHS, REACH, CE, FCC
Condition: New, factory-sealed