Where did you get that information?
BTW: using sbc-bench -m you can somehow inprecisely measure input voltage (especially drops under load): Realtime power usage - #12 by tkaiser or see below…
As for Rock 5B’s power requirements I really don’t know why everybody thinks 30W would be anything realistic/needed. These ‘30W’ are the rated wattage of Radxa’s USB PD PSU at 12V/2.5A which should be suitable for Rock 5B with lots of host powered USB peripherals and all SoC engines under full load.
If you’ve not lots of host powered USB peripherals and a ‘bad’ SSD with insanely high peak current requirements you’ll have a hard time ever exceeding 15W. When running stress-ng --matrix 0 for example consumption increases just by 10W (measured at wall with a 15W RPi USB-C power brick):
root@rock-5b:/home/tk# sbc-bench.sh -m
...
Time big.LITTLE load %cpu %sys %usr %nice %io %irq Temp DC(V)
11:19:13: 408/1800MHz 0.52 0% 0% 0% 0% 0% 0% 33.3°C 5.23
11:19:18: 408/1800MHz 0.48 0% 0% 0% 0% 0% 0% 32.4°C 5.21
11:19:24: 408/1800MHz 0.44 0% 0% 0% 0% 0% 0% 32.4°C 5.21
11:19:29: 2400/1800MHz 1.05 84% 0% 84% 0% 0% 0% 46.2°C 5.19
11:19:34: 2400/1800MHz 1.60 100% 0% 100% 0% 0% 0% 49.0°C 5.14
11:19:39: 2400/1800MHz 2.12 100% 0% 99% 0% 0% 0% 50.8°C 5.21
11:19:44: 2400/1800MHz 2.59 100% 0% 99% 0% 0% 0% 52.7°C 4.99
11:19:49: 2400/1800MHz 3.02 100% 0% 99% 0% 0% 0% 53.6°C 5.18
11:19:54: 2400/1800MHz 3.42 100% 0% 99% 0% 0% 0% 54.5°C 5.04
11:19:59: 408/ 600MHz 3.79 72% 0% 72% 0% 0% 0% 45.3°C 5.40
11:20:04: 408/ 600MHz 3.48 0% 0% 0% 0% 0% 0% 41.6°C 5.21
^C
BTW: every 5V power source that claims more than 15W/3A is nonsense anyway since the voltage drops when exceeding 15W are too much. There’s a reason none of the USB-C and USB PD power modes define anything at 5V that exceeds 3A.