On the newest version of the Mac Pro (newest as of January 2010) the Mac Pro uses a non-standard PCI-e power connection. Due to this unique power connection, the EVGA 285 Mac Edition is not compatible with this version of the Mac Pro.

Here are the offically support Mac Pro models:

• Mac Pro (Early 2009 with 1066Mhz DDR3)
• Mac Pro (Early 2008 with 800Mhz DDR2 FB-DIMM memory)

If you need to determin your version of your Mac Pro, please search by your Mac Pro serial number on Apple.com.

https://support.apple.com/specs/

If you have further question please contact EVGA Support.