[pbnjeh]

I don't have Pi 5 to check this, but from what I've read, it does not support PPS. And such support is required; otherwise, even with a source that supports PPS, the connection will behave in a non-PPS fashion.

Apparently, cable quality is also demonstrating itself to be a significant factor in the Pi 5 power supply environment.

Regarding both these points:

https://github.com/raspberrypi/rpi-eeprom/issues/497

[Dylan16807]

What??

Then how the hell does it negotiate the power and know if it's attached to 3A or 5A?

[gorkish]

Well, as it turns out, although a lot of stuff out there implies that the Pi uses USB-PD, it actually doesn't negotiate anything; it's just a dumb 5V peripheral. It can measure its own power (current/voltage) and has a current limit setting that the PMC will use to adjust clocks, etc. and alert on overcurrent conditions. If you hook up a higher amperage supply you have to change your boot config to the higher current limit. Everything is on you to make it work its weird not-quite-standards-compliant way.

The "Official Pi 5 USB-C Power Supply" is USB-PD compliant and as it is advertised as such in conjunction with the Pi5, I think that is where the confusion originates