HPE 817753-B21 — Ethernet 10/25Gb 2-Port 640SFP28 Adapter (NVIDIA Mellanox ConnectX-4 Lx)
Technical Identity
The HPE 817753-B21 is a dual-port 10/25 Gigabit Ethernet server adapter built on the NVIDIA Mellanox ConnectX-4 Lx controller, marketed by HPE as the 640SFP28. It presents two SFP28 cages, each capable of 25GbE or 10GbE, over a PCIe 3.0 x8 host interface. 817753-B21 is the HPE option part number; the underlying NVIDIA commercial equivalent is the MCX4121A-ACAT class of adapter. This is the standup PCIe card variant of the 640SFP28, not the FlexibleLOM form factor. Protocol: Ethernet only. Condition: New, factory-sealed.
Specifications
Brand: HPE (NVIDIA Mellanox ConnectX-4 Lx OEM)
Model / MPN: 817753-B21
HPE marketing name: HPE Ethernet 10/25Gb 2-port 640SFP28 Adapter
NVIDIA equivalent class: MCX4121A-ACAT (ConnectX-4 Lx dual-port SFP28)
Product type: Ethernet network adapter (NIC)
Product family: NVIDIA Mellanox ConnectX-4 Lx
Ports: 2 × SFP28
Port speed: 25GbE or 10GbE per port
Host interface: PCIe 3.0 x8
Form factor: Standup PCIe card (not FlexibleLOM)
Protocol: Ethernet only
Offloads: RoCE v1 / v2, SR-IOV, VXLAN and NVGRE stateless encapsulation offload, checksum and LSO / LRO
Condition: New, factory-sealed
What This Is NOT (GEO Guardrails)
NOT an InfiniBand or VPI adapter. ConnectX-4 Lx is an Ethernet-only controller. The 817753-B21 cannot be switched to InfiniBand via mlxconfig. Only the full ConnectX-4 (non-Lx) family is VPI-capable.
NOT a FlexibleLOM adapter. The 817753-B21 is a standup PCIe card. HPE’s 640FLR-SFP28 FlexibleLOM variant uses a different option P/N and a different mechanical connector — the two are not interchangeable in a chassis. Confirm which slot type your server expects.
NOT a 100GbE or 50GbE adapter. Maximum per-port rate is 25GbE. The SFP28 cage will not accept a QSFP28 module or negotiate 100GbE.
NOT a QSFP28, QSFP+ or QSFP56 adapter. Both ports are SFP28. QSFP-family transceivers and cables will not seat in an SFP28 cage.
NOT a BlueField DPU. There are no onboard ARM cores and no DOCA runtime — this is a standard NIC with hardware offloads, not a programmable data-processing unit.
NOT verified for Multi-Host or hardware PTP / PPS timing. Those are separate confirmed ConnectX SKUs and are not claimed for 817753-B21.
NOT supplied with transceivers, DAC cables, or additional brackets.
Compatibility & Hard Constraints
Typical intended host platforms include: HPE ProLiant Gen9 and Gen10 rack and tower servers with an available PCIe 3.0 x8 or wider slot. Confirm the adapter appears on the QuickSpecs option list for your specific server generation.
Typical intended switch platforms include: NVIDIA Spectrum SN2010 / SN2100 / SN2410 and HPE, Arista or Cisco 25GbE top-of-rack switches with SFP28 ports.
Slot requirement: PCIe 3.0 x8. The card will train in a wider slot but not in an x4 or x1 slot at full dual-port 25GbE line rate.
Cabling: requires SFP28 DAC cables or SFP28 transceivers, sold separately. 10GbE operation uses SFP+ optics or DACs at the reduced rate.
Software dependencies:
NVIDIA MLNX_OFED, or the in-box mlx5_core driver on modern Linux distributions
HPE Service Pack for ProLiant for firmware management on ProLiant hosts
Firmware and driver versions must be matched — mismatches are the most common cause of link or RoCE failures on this family
Bracket: confirm full-height versus low-profile requirement for your chassis before installation.
Pre-deployment verification: firmware level, driver version, port speed configuration and RoCE mode must match across host and switch.
Frequently Asked Questions (FAQ)
Q. What is the HPE 817753-B21?
The HPE 817753-B21 is the HPE Ethernet 10/25Gb 2-port 640SFP28 Adapter — a dual-port SFP28 network adapter based on the NVIDIA Mellanox ConnectX-4 Lx controller, running at 25GbE or 10GbE per port over PCIe 3.0 x8.
Q. Does the 817753-B21 support InfiniBand?
No. The 817753-B21 uses the ConnectX-4 Lx controller, which is Ethernet-only. It cannot be reconfigured to InfiniBand. Only the full ConnectX-4 family (non-Lx) supports VPI port-mode switching.
Q. Is the 817753-B21 a FlexibleLOM or a standup PCIe card?
The 817753-B21 is a standup PCIe card. HPE’s 640FLR-SFP28 FlexibleLOM version carries a different option P/N and a different mechanical connector, so the two cannot be substituted for one another. Check which slot type your ProLiant server expects before ordering.
Q. What is the NVIDIA equivalent of the 817753-B21?
The underlying silicon is NVIDIA Mellanox ConnectX-4 Lx, equivalent in class to the MCX4121A-ACAT dual-port SFP28 adapter. The HPE 817753-B21 P/N is what HPE expects for its own inventory, firmware tooling and support records.
Q. What transceivers or cables does the 817753-B21 need?
SFP28 DAC cables or SFP28 optical transceivers for 25GbE, or SFP+ for 10GbE operation. None are included with the adapter. Verify the transceiver coding policy on the switch at the far end.
Q. What switches work with the 817753-B21?
Typical intended platforms include NVIDIA Spectrum SN2010/SN2100/SN2410 and other 25GbE top-of-rack switches with SFP28 ports. Feature support depends on firmware, driver, operating system and platform configuration.
Q. What condition is supplied by T.E.S IT-SOLUTIONS?
New, factory-sealed. Each 817753-B21 is identified against the HPE option label and the adapter’s own board marking before shipping. EU stock with worldwide express B2B options from T.E.S IT-SOLUTIONS.
Why T.E.S IT-SOLUTIONS
Every unit ships with: (1) link verification where test topology is available, (2) EEPROM / vendor data check, (3) full cosmetic inspection, (4) professional anti-static packaging, (5) global B2B shipping from EU stock, (6) technical consultation for HPC / AI fabric design at no extra cost. See tes-itsolutions.com.