Dell 0TDNNT — Mellanox ConnectX-5 EN 25GbE Dual-Port SFP28 PCIe 3.0 x16 Adapter
Technical Identity
Dell OEM Mellanox ConnectX-5 EN network adapter (Dell PN 0TDNNT). Dual-port 25GbE SFP28 over PCIe 3.0 x16, Ethernet only (no InfiniBand). Dell PowerEdge qualified firmware, RoCE v2 / NVMe-oF / VXLAN / NVGRE / SR-IOV / GENEVE / Open vSwitch hardware offloads. Refurbished Grade A, EEPROM-verified, EU stock.
Specifications

Brand: Dell (OEM Mellanox ConnectX-5 EN)
Dell Part Number: 0TDNNT
Equivalent retail family: MCX512A-ACAT class (Dell SKU build)
Ports: 2 × 25GbE SFP28
Host interface: PCIe 3.0 x16
Protocol: Ethernet only (1/10/25 GbE per port)
ASIC: Mellanox ConnectX-5 EN
Qualification: Dell PowerEdge — Dell-signed firmware
RDMA / Storage: RoCE v1/v2, NVMe-oF, iSER, SMB Direct
Overlay offloads: VXLAN, NVGRE, GENEVE, Open vSwitch
Virtualization: SR-IOV (up to 128 VFs), VirtIO acceleration
Form factor: Low-profile PCIe (full-height bracket fitted; LP bracket supplied where available)
Condition: Refurbished Grade A — EEPROM-verified, link-tested, cosmetically inspected

What This Is NOT

NOT InfiniBand. This is the ConnectX-5 EN variant — Ethernet only. For IB use a ConnectX-5 VPI (MCX556A-EDAT) or ConnectX-5 IB (MCX555A-ECAT) part.
NOT 100GbE. Maximum 25GbE per port. For 100GbE use MCX516A-CCAT / MCX516A-CDAT.
NOT QSFP28. SFP28 cages only — accepts SFP28 / SFP+ / SFP cables and transceivers, never QSFP-class.
NOT a standard NVIDIA retail card. Dell OEM build — firmware is Dell-signed. Use in non-Dell hosts is possible but unsupported; verify before deploying.
NOT supplied with SFP28 transceivers, DAC cables, or AOC cables. Sold as the adapter only.

Compatibility
Hosts: Native fit and full Dell iDRAC / lifecycle-controller support on Dell PowerEdge 13G, 14G, 15G servers (R630, R640, R650, R730, R740, R740xd, R750, R7525, etc.). Will physically and electrically operate in any standards-compliant PCIe 3.0 x16 (or x8 at half bandwidth) slot, but firmware updates and full feature reporting require Dell OpenManage on a Dell host.
Switches (pairs with, not a category tag): Any 25GbE SFP28 ToR switch — NVIDIA Spectrum / Spectrum-2 (SN2010, SN2410, SN2700-class with SFP28 breakout), Cisco Nexus 93180YC, Arista 7050SX3 / 7280SR, Dell PowerSwitch S5224F-ON, Juniper QFX5120-48Y.
Cables & transceivers (pairs with, not a category tag): SFP28 25G DAC (e.g., MCP2M00-A001E / A002E / A003E), 25G SR SFP28 optics (MMA2P00-AS), 25G LR SFP28 optics (MMA2L20-AR), or any standards-compliant SFF-8472 SFP28 module. Backward compatible with SFP+ 10G and SFP 1G modules.
OS support: Windows Server 2016 / 2019 / 2022, RHEL 7/8/9, SLES 12/15, Ubuntu 18.04+, VMware ESXi 6.7 / 7.0 / 8.0, Proxmox VE, Citrix Hypervisor — using Dell-qualified inbox drivers or current MLNX_OFED / WinOF-2.
Frequently Asked Questions (FAQ)
Q. What is the Dell 0TDNNT?
The Dell 0TDNNT is an OEM Mellanox ConnectX-5 EN network adapter: dual-port 25GbE SFP28 on PCIe 3.0 x16. It is PowerEdge qualified and supports RoCE v2, NVMe-oF, SR-IOV, VXLAN, NVGRE and GENEVE hardware offloads.
Q. Is 0TDNNT InfiniBand capable?
No. The 0TDNNT is the EN (Ethernet) variant only. For InfiniBand (EDR 100Gb/s) you need a ConnectX-5 VPI part such as MCX556A-EDAT or an IB-only MCX555A-ECAT.
Q. How does 0TDNNT differ from Dell 0V5DG9?
Both are Dell OEM ConnectX-5 EN dual 25GbE SFP28 PCIe 3.0 x16 adapters. The difference is OEM build revision and Dell production batch — functionally and electrically equivalent in a Dell PowerEdge host.
Q. Can 0TDNNT be used in non-Dell servers?
Physically yes — it is a standard PCIe 3.0 x16 card. Operationally, the Dell-signed firmware may restrict feature reporting or block firmware updates outside a Dell iDRAC environment. Always validate in a lab before production deployment in HPE, Supermicro or Lenovo hosts.
Q. What condition does T.E.S IT-SOLUTIONS supply?
Refurbished Grade A — every unit is EEPROM-verified for correct Dell PN, link-tested on a 25GbE Spectrum switch, cosmetically inspected, and shipped from EU stock with multi-currency invoicing.
Why buy from T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS is a Europe-based data-center networking specialist focused on NVIDIA Mellanox and OEM-Mellanox hardware. Every Dell OEM ConnectX adapter we ship is MPN-identified, EEPROM-verified, link-tested on production switches, and cosmetically inspected before leaving our EU warehouse. Multi-currency invoicing (EUR / USD / GBP / CHF), worldwide express shipping, and free pre-sale technical consultation included.