Mac Pros released in early 2009 can now support six-core Xeon CPUs and faster 1,333MHz RAM thanks to a new firmware hack. By installing an EFI firmware update, users can convert their machine into a mid 2010 model Mac Pro.
Loading the new EFI firmware onto a 4,1 model (early 2009) Mac Pro updates it to a 5,1 model (mid 2010) machine, and users can upgrade their components beyond the earlier model’s official support.
This means users can install the most recent Westmere Xeon CPUs and 1,333MHz RAM. Though both machines are similar, the early 2009 model could only previously support 1,066MHz RAM. The firmware also enables the Mini DisplayPort to deliver audio signals over HDMI.
It’s worth noting that Apple doesn’t support this firmware update for the 2009 Mac Pro, and it doesn’t consider the CPU to be a user-upgradable part. Therefore, performing these upgrades is likely to void any AppleCare you may have on the machine. Users are yet to report any issues with installing the new firmware, and the process is reversible.