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FW16 PCIe x16 Expansion Bay

The FW16 PCIe x16 Expansion Bay is an open-source community hardware project by Ether-Nova that provides a fully powered PCIe x16 physical slot on a board designed to sit in the Framework Laptop 16's expansion bay shell12. The slot provides x8 electrical (PCIe Gen 4) since the Framework 16 exposes a maximum of 8 PCIe lanes through its expansion bay interface, and can deliver up to 75W of power123.

The project allows connecting any common PCIe device via risers or extenders, not just GPUs — the author explicitly designed the slot to be more general-purpose than GPU-only solutions1.

Prototype / In Development

This project is in the PCB prototype phase. The latest revision is V0.43 (committed March 24, 2026), with V0.4, V0.42, and V0.43 PCB designs in the repository. The author notes they are "not too familiar with PCIe protocol" and are testing whether the design works12.

Design Overview​

The board sits inside the Framework 16 expansion bay shell and exposes a standard PCIe x16 physical slot on the rear of the shell, allowing external PCIe devices to be connected via risers or extenders1. The Framework 16's expansion bay provides up to 8 PCIe 4.0 lanes through two 74-pin interposers — one primarily for power and one for PCIe, DisplayPort, and other high-speed signals3.

Power Delivery​

The slot is designed to deliver up to 75W at 12V, matching the PCIe specification for slot power1. The author is currently testing a buck converter to step down the Framework 16's VSYS_GPU rail (7–20V) to the 12V required by the PCIe slot1. The Framework 16's expansion bay can deliver significantly more power (up to approximately 200W at 20V), but the PCIe slot itself is limited to the standard 75W4.

PCB Design​

DetailValue
PCB layers4-layer1
Layer 1 (top)PCIe lanes1
Layer 2GND plane1
Layer 3PCIe lanes1
Layer 4 (bottom)Mainly GND plane + some power and signals1
PCIe lanesx16 physical slot, x8 electrical (Gen 4)1
Power75W max (12V via buck converter from VSYS_GPU)1

The author chose a 4-layer PCB with PCIe traces on the top and bottom layers and ground planes in between, following the PCIe specification's recommendation for trace placement1. Framework generally recommends 6-layer PCBs for high-speed PCIe signal integrity in the expansion bay, though community designs have demonstrated working results on 4-layer boards4.

Distinction from Other Expansion Bay GPU Projects​

This project is distinct from both the OCuLink module and the MXM adapter:

ProjectConnectorApproach
FW16 PCIe x16 Expansion BayRaw PCIe x16 slot1Direct PCIe slot for any device via risers
OCuLink eGPU ModuleOCuLink connectors4Native PCIe via OCuLink to external enclosure
Framework 16 to MXM AdapterMXM card edge5Mobile GPU modules (MXM form factor)
MXM GPU + Dell E-Port AdapterMXM + Dell E-Port6MXM GPU with dock integration

Technical Specifications​

SpecificationDetails
Target platformFramework Laptop 16 expansion bay1
Slot typePCIe x16 physical (x8 electrical, Gen 4)1
Power75W max at 12V (buck converter from VSYS_GPU)1
PCB layers4-layer1
Use caseAny PCIe device via risers/extenders (not GPU-only)1
StatusPCB prototype phase (V0.43 latest revision)12
SourceEther-Nova/FW16-pcie-expansion-bay (GitHub)2

Footnotes​

  1. Framework 16 Pcie x 16 slot for expansion bay — Framework Community (Pierre_Cruse / Ether-Nova, October 2025) ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15 ↩16 ↩17 ↩18 ↩19 ↩20 ↩21 ↩22

  2. Ether-Nova/FW16-pcie-expansion-bay — GitHub ↩ ↩2 ↩3 ↩4 ↩5

  3. GPU Interposer FW 16 — Framework Community (April 2025, power delivery discussion) ↩ ↩2

  4. OCuLink Expansion Bay Module — Framework Community (expansion bay specs, PCB layer recommendations) ↩ ↩2 ↩3

  5. Framework 16 to MXM Gpu - V0.1 Prototype design — Framework Community (Joe_Shapiro, August 2025) ↩

  6. a-little-wifi/frmw-16-MXM-E-port — GitHub (MXM + Dell E-Port adapter) ↩