The above suggested settings only affect cpufreq behaviour with I/O workloads and have been adopted by Radxa recently.
As for powering using 5V at 4A is nonsense since you get either/or but never both at the same time with this kind of cabling. Ohm’s law still is in place and both cable and contact resistance will result in underpowering (most probably undervoltage).
You can use my sbc-bench to monitor the input voltage in a way similar to here: Realtime power usage
If it drops below 5V already at idle you know your cabling is at fault.