Install Expansion Cards in Mac Pro
You can configure your Mac Pro by installing additional cards in the PCI Express expansion slots.
Note: If you have a Mac Pro rack workstation, see Install Expansion Cards in Mac Pro.
Slots 1 and 3 are x16 slots that directly connect to the CPU; they provide the highest performance and should be used first. After that, it’s preferable to connect a card to a slot that has as at least as many lanes as the card. If you ordered an Apple Afterburner card with your Mac Pro, the card comes installed in slot 5. If you’re installing an Afterburner card, use a PCI Express x16 slot for optimum performance. See the table below for details.
Number of lanes
x4 (Reserved for the rear I/O card)
x16 (Use first)
x16 (Use first)
Mac Pro has four double-wide slots and three single-wide slots, which can be customized with cards to expand Mac Pro capabilities. The half-length slot is pre-populated by the Apple I/O card, but this card can be removed and other half-length PCIe cards installed.
WARNING: For optimum ventilation, space cards out as you install them. If you remove a card and don’t install a replacement, place a port access cover over the empty slot to keep foreign objects out of the enclosure. An uncovered slot affects the airflow that cools the internal components, and may cause damage.
Important: Connect cards to the appropriate power source, as illustrated below. Only use the original cables that came with your Mac Pro or cables sold online at apple.com or at an Apple Store. Only cables made specifically for Mac Pro are approved for use with PCIe modules.
Take care when connecting to the AUX connectors. When installing an accessory into your system that uses AUX power, first attach the AUX connector, then install the module. Be careful not to drop the module while connected to the AUX connector, as doing so may result in damage to the AUX connector or logic board. If the AUX connector becomes damaged, don’t turn on your computer because doing so may further damage it. Take your computer to an Apple Authorized Service Provider or Apple Store for repair.
Note: If Mac Pro encounters an error with a PCIe card, the status indicator light flashes amber twice and repeats until the computer is turned off. For more information, see the Apple Support article Mac Pro (2019) status indicator light behavior.
Follow these steps to install expansion cards in your Mac Pro.
Turn off your Mac Pro by choosing Apple menu > Shut Down.
Let it cool down for 5 to 10 minutes before you touch the internal components, which may be hot.
Disconnect all cables except the power cord from your Mac Pro.
Touch the metal on the outside of your Mac Pro to discharge any static electricity.
Note: Always discharge static before you touch parts or install components inside your Mac Pro. To avoid generating static, don’t walk around the room until you finish installing the expansion cards.
Disconnect the power cord.
Unlock the computer’s housing by rotating the latch counterclockwise 90 degrees.
WARNING: Do not rotate the latch while the computer is turned on; doing so may cause the computer to shut down.
Remove the computer’s housing by pulling it up by the latch.
Note: Mac Pro will not start up when the housing is removed.
Remove the side bracket.
Slide the lock to the right.
Remove the slot covers.
Remove the new card from its static-proof bag and hold it by its corners. Don’t touch the gold connector or the components on the card.
Note: Use only PCIe modules that are safety certified (CSA, UL, or equivalent) and specifically state that they are compliant with the industry standard PCIe specification. Noncertified, noncompliant modules may not keep different input power sources separated, resulting in a possible burn hazard.
Slide the card into place.
Slide the lock to the left.
Reinstall the side bracket.
Replace the computer’s housing, then turn the latch clockwise 90 degrees to lock it.
The computer will not turn on if the housing has not been replaced and the latch rotated to its original position.
Reconnect all cables and the power cord to your Mac Pro.