Choose the PCIe Topology Before the Auxiliary Kit

A network rate does not describe the complete path between an adapter and its host. The primary PCIe slot, an optional extension path and the server’s CPU topology are different design decisions. Document them independently before selecting a card or accessory.

Start with the server interface

MCX755106AS-HEAT is a stand-up HHHL ConnectX-7 card with two QSFP112 ports. Its primary interface is PCIe 5.0 x16 and its optional extension is described as Gen 4 x16. MCX753436MS-HEAB instead uses an OCP 3.0 SFF connection with thumbscrew/pull-tab retention. Its listed Multi-Host and Socket Direct capabilities do not make it mechanically interchangeable with the stand-up card. First identify the actual server slot, retention system and supported lane routing.

Separate primary and extension generations

C8180 and C8240 use PCIe 6.0 x16 as the primary interface in their exact specifications. C8240’s optional passive-card path is described separately as Gen 5 x16. Do not copy the primary interface’s generation into the accessory field. Conversely, an unresolved accessory table does not erase the clearly documented primary-card specification.

The C8180X auxiliary kit, 930-9XAX6-0025-000, needs this distinction particularly carefully. Its ordering description says Gen 6, while package and technical tables use inconsistent Gen 5 and transfer-rate language. Preserve the known kit identity, 250 mm MCIO harness and auxiliary-card role. Keep the unresolved electrical-generation field out of an unqualified public specification until the exact assembly is confirmed.

Confirm what is included

NVIDIA explicitly states that the MCX755106 Socket-Direct-ready card kit excludes the passive auxiliary card and its two harnesses. A ready connector is therefore not a complete installed topology. Record the primary card, auxiliary board, harnesses, brackets, attachment points and firmware mode as separate bill-of-materials lines. Check cable length against the actual server route rather than choosing only by the suffix of a previous installation.

Define the acceptance record

For the completed system, record its physical topology, negotiated PCIe generation and width, NUMA placement, configured network protocol and supported port mode. Run a representative workload with the intended optics and cooling arrangement. A link-up test demonstrates basic connectivity; it does not by itself establish application bandwidth, isolation between hosts or resilience during failure recovery.

This checklist turns a family capability into a reviewable integration plan while keeping documented hardware facts separate from measurements that must come from the finished server.

Scope: Exact named topology distinctions; original qualification method, not a claim of certified server compatibility.

Public references

• ConnectX-7 ordering information
• Specifications | NVIDIA ConnectX-7 Adapter Cards User Manual
• ConnectX-7 OCP 3.0 ordering information
• Specifications | NVIDIA ConnectX-7 Cards for OCP Spec 3.0 User Manual
• Specifications | NVIDIA ConnectX-8 SuperNIC User Manual
• PCIe Auxiliary Card Kit | NVIDIA ConnectX-8 SuperNIC User Manual
• PCIe Auxiliary Kit Technical Specifications | NVIDIA ConnectX-8 SuperNIC User Manual