I don't think there's any limitation to 400, AFAIK.
There would need to be AuraSync compatible devices attached though, as IIRC, the TUF lineup has no onboard controllable lighting.
As an aside, if you're gaming and anything uses EasyAntiCheat, AuraSync is (or was, as of a few weeks ago) detected as cheat software and titles using EAC won't launch unless you disable "LightingService.exe" from TaskManager.,
That may explain why I could not find a link to AuraSync on the TUF B350M Gaming board's website. (I'm installing a Wraith Max cooler and wondered if I could use the USB cable or not)
I guess I could jus download AuraSync and see if it works. Should pose no harm,right? It will either work or report incompatibility.