The iOS 26.3 release candidate contains references to a pair of unreleased chips that are in the M5 family, according to information found by Nicolás Alvarez and shared with MacRumors.
iOS 26.3 RC mentions two unreleased SoCs, the T6051 and T6052, with the associated platform names H17C and H17D. 17 is a reference to the M5, as the standard M5 chip is numbered H17G. Typically, the “C” designation is used for Max chips and the “D” designation is used for Ultra chips. G is used for standard chips and S is used for Pro chips.
Using Apple’s previous numbering and lettering as a reference, this would suggest so M5 Max and M5 Ultra chip. There’s no current reference to the T6050 H17S, which is the chip identifier and platform name we’d expect for the M5 Pro.
Since we’re currently waiting for the new MacBook Pro versions with the M5 Pro and M5 Max chips, the chip references are a bit confusing. We have three options: the M5 Pro chip is there along with the M5 Max and M5 Ultra chips and it’s just not yet added to the iOS 26.3 code, Apple is changing its numbering, or Apple is planning M5 Max and M5 Ultra MacBook Pro models.
- Chip 1 in beta: T6051, H17C. Probably M5 Max.
- Chip 2 in beta: T6052, H17D. Probably the M5 Ultra.
- Not in beta: T6050, H17S. A chip identifier is expected for the M5 Pro.
Apple’s past Max chips have all used “C” designations, including the M1 Max (H13C), M2 Max (H14C), M3 Max (H15C/H15M), and M4 Max (H16C). There was also an M variant, the M3 Max, for the 14-core chip, with Apple using the C for the 16-core chip.
All Ultra chips have a “D” designation, including the M1 Ultra (H13D), M2 Ultra (H14D) and M3 Ultra (H15D). There was no M4 Ultra chip.
It’s not clear why we’re only seeing signs of the M5 Max and M5 Ultra chip, but rumors suggest that new MacBook Pro models with higher-end M5 chips are set to launch in the next few weeks. Apple is said to be working on a Mac Studio in the M5 family that would use the M5 Ultra chip, but we haven’t heard rumors of an imminent launch.