The scientific explanation is that these white FFC cables are usually not good enough for PCIe. There are better ones, but I don't trust this.Those flat cables for PCIe and cameras must require a certain protection from other wires and metal cases to avoid capacitance issues. Are there any requirements published?
I guess the PCIe cable is more sensitive than the camera cables. I had a problem with a Pi 5 PCIe cable touching a steel case for about 10 mm. An 80 GSM paper layer did not fix the issue. I carefully manufactured an isolation unit from 120 GSM paper folded over three times and the problem disappeared. Then I switched to a non metal case for easier access. I thought there might be something more scientific.
If you need a reliable soultion switch to a CM5 with a suitable carrier board. These Hirose mezzanine connectors are pretty good in terms of signal integrity and are good even for PCIe Gen 4.
Statistics: Posted by fchk — Sat Dec 27, 2025 5:06 pm