I had a similar issue after installing Manjaro XFCE recently. Had to hard reset my computer each time it went to sleep as the screen would have frozen.
Yesterday I switched from the nouveau to the Nvidia driver and since then haven't had this issue.
Pin 1 is V_BUS, +5 V.
Take a USB cable and horribly mangle it,
to insert a 1-ohm resistor inline with the pin 1 conductor.
Run your USB workload and
measure voltage drop across the resistor with a DMM or similar.
V = I * R and P = I * V, so with R = 1 the millivolts you read
will be identical to the milliamps drawn by the device,
and power will be five ...