VX100 and AXM2 Reference for DIY AI Hardware Projects

Pigeon Labs Stack published v0.1.0-reference, an open-source reference kit of pin mappings, NVLink connection plans and KiCad 10.0.7 starter files for building carrier boards around NVIDIA V100 SXM2 modules. The kit documents 800 canonical contacts — 400 on connector A and 400 on connector B — plus two- and four-GPU NVLink connection tables and three editable KiCad starters, with the author describing the contribution as primarily curation of existing public reverse-engineering work. The release is a public reference pre-release, not a hardware-qualified carrier board, and notes that each V100 requires a 156.25 MHz differential NVHS clock on B/E20 (+) and B/F20 (−) and a separate 100 MHz PCIe clock on A/E7 (+).

This project aims to become an open-source carrier-board design for NVIDIA V100 SXM2 modules , including NVLink connections for two- and four-GPU configurations. While that board is being developed, this reference kit shares the pin mappings, connection plans and connector-only KiCad resources so other people can develop their own designs. My contribution so far is primarily curation: gathering public information, comparing sources, reconciling connector orientation and signal names, and making the results easier to follow. The original reverse-engineering work belongs to its authors, credited in Sources and attribution https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/sources.md . 1. Download the complete reference ZIP from v0.1.0-reference https://github.com/pigeon-labs-stack/v100-sxm2-reference/releases/tag/v0.1.0-reference , or use Code Download ZIP for the current development files. 2. Extract the archive and keep the directory structure. Choose a single-, two- or four-module KiCad starter https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/README.md , then open its .kicad pro file in KiCad 10.0.7 or a compatible newer version. Keep the whole kicad/ folder so the shared symbol library is available. 3. For reading without KiCad, use the complete schematic PDFs https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/downloads.md read-without-kicad or standalone workbook https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/workbook/V100-SXM2-Pinout-and-NVLink.xlsx . The download guide https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/downloads.md includes print editions and library-path help. Change notes https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/CHANGELOG.md identify reference editions. This is a public reference pre-release, not a hardware-qualified carrier board. | I want to… | Start here | |---|---| | Find a contact on connector A or B | Pin maps and naming https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/pinout.md | | Plan a connection between two V100s | Two-GPU NVLink guide https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/nvlink-2gpu.md | | Plan a four-V100 interconnect | Four-GPU NVLink guide https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/nvlink-4gpu.md | | Use the connector symbols in my own design | KiCad starter and previews https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/kicad.md | | Start with two or four V100s already connected by NVLink | Choose a KiCad starter https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/README.md | | Work offline with the full reference | Download the standalone workbook https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/workbook/V100-SXM2-Pinout-and-NVLink.xlsx | | Browse or print every schematic sheet without KiCad | Complete PDF sets https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/downloads.md read-without-kicad | | Check what is established and what is open | Status and limitations https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/status.md | - 800 canonical contacts: 400 on connector A and 400 on connector B, with signal names, evidence and electrical-treatment notes. - Two- and four-GPU connection tables: exact Connector B pads, directions, lanes and polarity. - Three editable KiCad starters: one module’s A/B connectors, plus two- and four-module versions with NVLink data connected. Every contact stays labelled, including unconnected clocks, power and control pins. No regulator, power-control or clock circuits are included. - Catppuccin Mocha visuals: contact maps, topology diagrams, schematic previews and the standalone dark reference workbook. An optional KiCad colour theme is included. External clock required: the NVLink starter schematics show data wiring, not a complete working NVLink implementation. Each V100 needs a 156.25 MHz differential NVHS clock on B/E20 + and B/F20 − . The separate PCIe clock is 100 MHz on A/E7 + and A/F7 − . Clock requirements and scope https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/kicad.md external-clocks-required . These are the actual connector-only KiCad schematics : 400 labelled contacts on A and 400 on B. Click a preview to open the full-size vector drawing. The two- and four-GPU NVLink arrangements are shown separately below and in the connection guides. Open the KiCad project https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/V100 Connectors.kicad pro · Schematic overview https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/previews/Overview.svg · KiCad guide https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/kicad.md The full six-group two-GPU arrangement is derived from the documented pairing families; the four-GPU arrangement follows the curated topology. Each guide explains its source evidence and remaining uncertainties. These are logical connection plans, not routed bridge schematics. Open the two-V100 KiCad project https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/2-V100/V100 2GPU NVLink.kicad pro · Native schematic previews https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/2-V100/README.md Open the four-V100 KiCad project https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/4-V100/V100 4GPU NVLink.kicad pro · Native schematic previews https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/kicad/4-V100/README.md Two-GPU connections https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/nvlink-2gpu.md · Four-GPU connections https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/nvlink-4gpu.md The actual local reference footprint, exported directly by KiCad: 800 contact pads, housing outlines and mounting features. A raw PCB footprint is not included in this edition; see footprint availability and open questions https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/footprint.md and visual provenance https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/visuals.md render-provenance . This is a render of an existing project geometry preview, using the Amphenol connector model. It illustrates connector placement; it is not a completed carrier board or proof of connector A/B identity, mating-part selection or viewing direction. See render provenance https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/visuals.md . The longer-term goal is a reusable open-source board design. This reference kit currently covers the pin mappings, NVLink connection plans and connector starter. Routed boards, manufacturing outputs and hardware qualification are future work. See the roadmap https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/docs/status.md roadmap . Corrections are particularly useful when they include an oriented drawing, exact source reference, continuity result or measured behaviour. Please distinguish a confirmed observation from an interpretation. Use the correction and file-help forms https://github.com/pigeon-labs-stack/v100-sxm2-reference/issues/new/choose , following the contribution guide https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/CONTRIBUTING.md . To reference this edition in your own work, use GitHub's Cite this repository option or CITATION.cff https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/CITATION.cff , and retain the relevant upstream source credits. Our original hardware design contributions use CERN-OHL-W-2.0 ; our original documentation, diagrams and workbook presentation use CC BY-SA 4.0 . Both allow commercial reuse, with attribution/notices and the applicable reciprocal sharing requirements. See licence scope and full texts https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/LICENSE.md and third-party notices https://github.com/pigeon-labs-stack/v100-sxm2-reference/blob/main/THIRD PARTY NOTICES.md . The licences do not claim ownership of pinout facts or replace upstream terms. Follow the project and join the discussion on the Level1Techs forums: designing an open-source budget 4× V100 SXM2 NVLink backplane https://forum.level1techs.com/t/designing-an-open-source-budget-4x-v100-sxm2-nvlink-backplane-passive-pcie-vs-pex8749/250801 . Thank you to everyone on the Level1Techs forums https://forum.level1techs.com/ for your help, ideas and contributions to this project.