Looking at the 2017 nTB for my next Mac. Been reading threads here that say that the TB version has two fans and hence they do not turn on as often as the single fan on nTB MBP. Just wondering how big an issue, the fan noise is on the nTB model, if at all? Also in what scenarios does the fan usually turn on - YouTube, Netflix, Chrome tabs etc.? And when it turns on, is it obviously and annoying loud?