Apple’s top-tier M3 Ultra chip is presently exclusive to the Mac Studio; however, a recent leak has disclosed that Apple has also tested this chip in the MacBook Pro.
In a post shared today on the Chinese social media site BiliBili, an unfamiliar user reported discovering code references to unreleased 14-inch and 16-inch MacBook Pro models equipped with the M3 Ultra chip, found within an internal build of iOS 18 operating on an iPhone 16 engineering prototype. The user specifically mentioned locating the codenames J514d and J516d in a file situated in the /AppleInternal/Diags/Tests/ directory.

The codenames J514 and J516 correspond to the 14-inch and 16-inch MacBook Pro models featuring M3 Pro and M3 Max chips, which Apple unveiled in October 2023. Notably, these specific codenames include a “d” suffix, likely indicating an Ultra chip variant. For instance, the Mac Studio utilizing the M3 Ultra is designated with the codename J575d.
Apple has yet to launch a MacBook Pro with an Ultra chip, making this finding significant. At present, the M3 Ultra stands as the fastest Mac chip ever released by Apple. It boasts up to a 32-core CPU, an 80-core GPU, and supports up to 512GB of unified memory, suggesting that these could have been the specifications for the MacBook Pro in an alternate scenario.
M4 MacBook Pro models released last year
Instead, Apple opted to refresh the 14-inch and 16-inch MacBook Pro models with M4, M4 Pro, and M4 Max chip options in October of the previous year. It is likely that Apple chose not to offer the M3 Ultra chip in the MacBook Pro, possibly due to the increased thermal and battery life challenges associated with laptops compared to desktop systems.
With the M4 Max, the MacBook Pro can be configured to include up to a 16-core CPU, a 40-core GPU, and up to 128GB of unified memory.
In summary, it appears that Apple contemplated the possibility of MacBook Pro models featuring the M3 Ultra chip, though it is improbable that they will ever make it to the market.