MCX556A-ECAT: NVIDIA ConnectX-5 VPI Dual-Port 100Gb/s EDR InfiniBand and 100GbE QSFP28 PCIe 3.0 x16 Adapter
Also listed as: ConnectX-5 VPI 100G, MCX556A-ECAT-SP, MCX556A, MCX556A-EDAT · made by Mellanox
The NVIDIA ConnectX-5 VPI dual-port adapter (model MCX556A-ECAT) features Virtual Protocol Interconnect (VPI) enabling each QSFP28 port to operate as either 100Gb/s EDR InfiniBand or 100GbE Ethernet. Connecting through a PCIe 3.0 x16 slot, it delivers up to 200Gb/s total throughput with full RDMA offloads, GPUDirect RDMA, and hardware MPI offloads for supercomputing clusters. When buying used ConnectX-5 VPI cards, check port protocol configuration via mlxconfig, inspect thermal sink condition, and confirm link sync on both ports.
Specifications
| Part number | MCX556A-ECAT |
|---|---|
| Brand | NVIDIA |
| Made by | Mellanox |
| Type | Network adapters |
| Other numbers | ConnectX-5 VPI 100G, MCX556A-ECAT-SP, MCX556A, MCX556A-EDAT |
| Status | current |
| Interface | PCIe 3.0 x16 |
| Form factor | PCIe Low Profile |
| Ports | 2x 100Gb/s QSFP28 |
| Speed | 100Gb/s EDR / 100GbE |
| Generation fit | PCIe Gen3 and Gen4 enterprise and HPC servers |
About the MCX556A-ECAT
MCX556A-ECAT is NVIDIA's ConnectX-5 VPI dual-port 100Gb/s adapter, featuring Virtual Protocol Interconnect (VPI) enabling each QSFP28 port to operate as either 100Gb/s EDR InfiniBand or 100GbE Ethernet. Connecting over a PCIe 3.0 x16 slot, it delivers up to 200Gb/s aggregate bandwidth with GPUDirect RDMA, hardware MPI offloads, and NVMe-oF acceleration for HPC clusters.
Compatibility
Requires an electrical and mechanical PCIe 3.0 x16 slot in high-performance enterprise and GPU servers. Features two QSFP28 ports supporting 100G EDR InfiniBand or 100GbE optical transceivers and copper cables. Port modes are independently selectable via mlxconfig. Low-profile and full-height brackets are supported.
How to identify a genuine unit
The card features a black or green PCB with an NVIDIA/Mellanox barcode label displaying model MCX556A-ECAT and PSID MT_0000000010. In system management utilities, the mlx5_core driver reports two dual-protocol VPI interfaces capable of 100Gb/s operation.
Buying used
Check port protocol configuration via mlxconfig to verify whether ports are currently configured for InfiniBand or Ethernet mode. Inspect the two QSFP28 cages for debris or bent contacts. Confirm that the heatsink is tightly seated and passes thermal checks.
Reference prices (last 14 days, updated 2026-10-27)
New: USD 680 (1 sighting, Oct 2026)
Used: USD 380 (1 sighting, Oct 2026)
All sightings
| Seller | Condition | Price | Note | Seen |
|---|---|---|---|---|
| serversupply.com | new | USD 680 | 2026-10-27 | |
| ebay.com | used | USD 380 | 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
- Dell 540-BBSZ Dell Mellanox ConnectX-5 Dual Port 100GbE QSFP28 PCIe Adapter
FAQ
What is VPI on the ConnectX-5?
Virtual Protocol Interconnect lets ports be independently set to InfiniBand or Ethernet protocol mode.
Does MCX556A-ECAT support GPUDirect RDMA?
Yes, enabling direct memory transfers between GPUs and network adapters without CPU overhead.
Buying or selling MCX556A-ECAT?
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 VPI Adapter Cards User Manual, checked 2026-10-27