I have a peoblem with my led strip when running anythin with fastled library, or anything with more than 4 leds on at the same time. i try example of running the the fiery led program and the first part of the strip stays yellow and some randoms at the end are blue/green.
Also noticed that if i run one blue led running from start to end, the last one was red. but the problem was only with fastled library. Not when making my own code.
Actually, you can power up to about 50 Neo's directly from 5V. But you have to strictly limit the brightness in software. I considered the USB current, took that and reduced it to a conservative value, divided that by 50, and by trial and error found max value that if applied to all 3x50 dies, was strictly limited to the total max current (of about 1A). But any software mistake that you make crashes the whole thing so you have to wade in carefully...