NVIDIA MMA4Z00-NS400 / 980-9I51S-00NS00 Compatible 400G OSFP SR4 Flat-Top (RHS) Transceiver — MPO-12/APC, 850nm MMF, for ConnectX-7

Flat-Top (RHS) — the NIC-side module, not the switch-side module

NVIDIA MMA4Z00-NS400 / 980-9I51S-00NS00 compatible — 400G OSFP SR4, 850nm multimode

→ NVIDIA OSFP part-number crosswalk — Mellanox MMA/MMS numbers mapped to the new NVIDIA 980- numbers, with form factor, optics and the correct part for each end of the link.

Mellanox Part Number: MMA4Z00-NS400
NVIDIA Part Number: 980-9I51S-00NS00
Description: Single-port OSFP SR4 optical transceiver, 400Gb/s, flat-top / Riding Heat Sink (RHS), MPO-12/APC, multimode

This is the flat-top module — the one that goes in the server, not the switch. If you are populating a single-port OSFP port on a ConnectX-7 or ConnectX-8 adapter, this is the correct part. Those ports carry their own heatsink built into the port cage, and it rides down on top of whatever module you insert. A finned module has no clearance underneath it and will not seat.

NVIDIA now calls this form factor RHS, for Riding Heat Sink — the equipment's heatsink rides on the module. Older documentation, existing BOMs and most purchase histories still say "flat-top." Same part.

Which One Do I Need?

The fins are either on the module or on the equipment. Never both, never neither.

A BlueField-3 does not take this module. NVIDIA states that BlueField-3 adapters accept QSFP112 devices only, and that OSFP is not for use in BlueField-3 DPUs. The equivalent part there is the MMA1Z00-NS400 — the same 400G SR4 optics in a QSFP112 shell, on the same MPO-12/APC fiber. If a BlueField-3 line is on your PO, that is the part to order, not this one.

The two parts are designed as a pair: one twin-port finned module in the switch → two MPO-12/APC patch cords → two flat-top modules in two ConnectX-7 servers. One switch module serves two servers.

Technical Specifications

Note on Reach: Why You'll See Both 50m and 100m

NVIDIA specifies 50m over OM4 for this module — and 30m over OM3 — and that is the figure to design against in an InfiniBand fabric. The optics are built to the SR MSA, which permits up to 100m over OM4 — so both numbers are correct, they just answer different questions. The standard describes what the optics can do under ideal conditions; NVIDIA's number is what they will support.

Usable reach past 50m depends on fiber grade and how many MPO matings sit in the path, because every additional mating costs optical budget. A 90m run through three patch panels is exactly where link margin quietly disappears. Design to 50m for NVIDIA support parity. Planning a longer run? Talk to us first.

Good to Know

• A finned-top (IHS) module will not physically seat in a ConnectX-7 OSFP port — the cage heatsink is in the way. This is the most common wrong order on this part.
• DGX H100 / H200 front cages do not take this module. They are twin-port OSFP flat-top cages — four of them, each feeding two ConnectX-7 controllers — so they need an 800G twin-port flat-top module. Count the optical ports on the cage, not just the top style. A ConnectX-7 adapter card in a standard server does take this part.
• 800G is not an upgrade at the server end: the ConnectX-7 single-port OSFP port is a 400G port.
• MMA1Z00-NS400 is one character away and is QSFP112 — a different cage entirely. It will not fit an OSFP port, and it is the part a BlueField-3 takes.
• MMS4X00-NS400 is single-mode DR4 at 1310nm, 500m. The MMA / MMS prefix is the tell: MMA is multimode, MMS is single-mode.
• Running single-mode? This is not your module. Tell us what the fiber plant is and we will point you at the right part rather than sell you this one.
• Your existing MPO cords probably will not work. NDR optics need MPO-12/APC — angle-polished, Type B, female. The UPC cords in a 100G or 200G fabric cannot mate with them. Here is the full fiber guide.
• DGX H100 front cages and liquid-cooled deployments need the 800G flat-top variant (MMA4Z00-NS-FLT), which we do not stock. We will still tell you what to look for.

Quick Checklist — Is This the Right Module?

You are populating a single-port OSFP port on a ConnectX-7 or ConnectX-8 adapter. The port cage has its own heatsink and one optical port. Your fiber plant is multimode (OM3 or OM4) with MPO-12/APC connectors. Your runs are 50m or shorter. You want 400G NDR InfiniBand or 400G Ethernet.

Availability

In stock at Resilient Tec · Additional units ship on a 7–10 day lead time.
Building a cluster? Tell us how many ports you are populating and we will quote the switch-side and server-side modules together. Request a quote →

Warranty: lifetime, backed by Resilient Tec — not a manufacturer term. When a module fails you reach a named seller in the US, not a ticket queue.

You Might Also Need

• 800G OSFP SR8 Finned-Top (IHS) twin-port transceiver — the switch-side half of the link. One of those serves two of these.
• MMA1Z00-NS400 — 400G QSFP112 SR4 — the same optics in a QSFP112 shell, for BlueField-3 DPUs and ConnectX-7 QSFP112 adapters
• MPO-12/APC OM4 multimode trunk cable, Type B, female-to-female — one per module, $59.00 to $139.00, 1 m to 20 m
• MFP7E10-N005 MPO-12/APC multimode patch cord, 5 m — genuine NVIDIA, the fiber between the two modules
• MPO-12/APC 1:2 splitter cables — built to order, for NDR200 fan-out from one twin-port switch port
• OSFP DAC cables — when the run is short enough that copper beats optics
• Product guides — structured cabling, switches and the rest of the rack

Related Guides

Does the MMA4Z00-NS400 Work With My System? ConnectX-7, BlueField-3, Quantum-2 and DGX H100 Compatibility

Flat-Top or Finned-Top OSFP? How to Tell Which Module Your ConnectX-7 Actually Needs

MPO-12/APC vs UPC: Why Your Existing Fiber Won't Work With NDR Optics

NVIDIA OSFP Part-Number Crosswalk: Mellanox MMA/MMS to NVIDIA 980- Numbers

OSFP vs. QSFP-DD: A Practical Breakdown for GPU Clusters