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Conclusion

Conclusion

DIY or Buy?

DIY

AdvantagesDisadvantages
  • Can reach PCIe 3.0 speeds
  • Can be designed to fit in any enclosure
  • Cheaper per-unit cost
  • Can be modified with different connector (MCIO)
  • Cannot reach PCIe 4.0 speeds
  • Significant performance loss in synthetic benchmarks
  • Expensive to manufacture when considering minimum order quantity of PCBs and components and soldering equipment
  • Time consuming to manufacture especially including electrical testing
  • Unclear if design needs overhaul to reach PCIe 4.0 without having equipment to test circuit at PCIe 4.0 speeds

Buy

AdvantagesDisadvantages
  • Can reach PCIe 4.0 speeds
  • Beats PCIe 3.0 adapters in synthetic benchmarks
  • Flexible micro-coax can be bent to fit most scenarios
  • Cost is low considering performance and quality of adapter
  • Minimum length of adapter is 12cm which might make it too long even with bending

Conclusion

Image 25. Aliexpress M.2 Oculink PCIe 4.0 silver plated extension cable (source)
  • Buying the Aliexpress M.2 Oculink PCIe 4.0 adapter is the much more sensible option.
  • It works out of the box and requires minimal bending to fit into your enclosure.
  • Also comes in a variety of lengths: [15cm, 20cm, 25cm, 30cm, 40cm].

Future plans

  • Check mini cool edge IO (MCIO) connector:
    • Has a better official number of insertion cycles.
    • Cables are designed officially for PCIe 4.0 speeds.
  • Fix performance problems and see if PCIe 4.0 speeds can be reached.
    • Redesign hatch plane and taper in flexible PCB design.
    • Use a low loss dielectric to reduce dielectric losses at PCIe 4.0 speeds.
    • Use smooth copper foil to reduce skin effect losses.
  • Determine if there is a method to cheaply verify performance at PCIe 4.0 speeds.
    • High frequency oscilloscopes (>20GHz) required for PCIe testing are extremely expensive.
    • Most low cost (<$1000) and low frequency (<200MHz) oscilloscopes are not useful for validating PCIe peformance.
Discussion