Apple has released SMC Firmware Update 2.0 for the new Mac Pro. It’s a 544KB download.
This update enables Mac Pro to enter Power Nap without running the fan for most Power Nap activities. It also addresses a rare issue where a low-speed USB device may not be detected at boot.
Apple says the update is recommended for all Mac Pro (Late 2013) models. You can download it at http://tinyurl.com/mbaevwk .