Apple's Mac Pro SMC Firmware Update 2.0 tweaks system control settings to allow certain Power Nap processes to run without spooling up the fans. The exact Power Nap activities covered in the updated settings were not detailed in the release notes.
First announced with OS X 10.8 Mountain Lion, Power Nap is an energy-saving feature that allows Macs to keep up to date even while sleeping. For example, with Power Nap enabled, Mail is able to collect new messages in the background without waking the Mac from sleep.
Wednesday's update also fixes a rare issue in which low-speed USB devices were not being detected at boot.
Apple's firmware update comes over two months after the company released an EFI update addressing various bugs in December before the computer shipped out to customers.
Recommended for all late-2013 Mac Pro models, the Mac Pro SMC Firmware Update 2.0 comes in at 544KB and can be downloaded via Apple's Support Downloads webpage or Software Update.