Apple iOS 26.3 RC Hints M5 Max and M5 Ultra in Chip Lineup

Apple has seeded the release candidate (RC) versions of iOS 26.3 and iPadOS 26.3 to developers for testing. The RC includes references to two unreleased M5 chips, with model numbers T6051 and T6052, and platform names H17C and H17D. Observers say the naming patterns point to the M5 Max and M5 Ultra configurations, based on how Apple has labeled prior chips.

A user on X, Nicolás Alvare, spotted these references in the iOS 26.3 RC, and MacRumors highlighted the link to the M5 generation. The code does not reference other models that would normally correspond to an M5 Pro, such as T6050 or H17S, which raises questions about internal naming or whether the Pro tier is present in this RC.

Chip naming patterns and what they imply

Historically, Apple has used letters to distinguish chip lines: C for Max, D for Ultra, G for standard, and S for Pro. In this RC, T6051/H17C are associated with the M5 Max, while T6052/H17D are linked to the M5 Ultra, according to the report. Whether Apple has altered its internal naming or simply omitted the M5 Pro from this build remains unclear.

The absence of T6050 or H17S in the RC suggests a naming shift or an incomplete Pro listing for this release. Officials involved in the beta cycle have not publicly confirmed changes to the M5 Pro lineup.

MacBook Pro Refresh and Mac Studio Under Next-Gen Chips

Apple is expected to launch updated MacBook Pro models powered by the M5-series chips alongside macOS 26.3. The launch could occur in February or March 2026. There is also a rumour of an M5 Ultra-powered Mac Studio, which would align with the M5 Ultra tag seen in the RC codes.

In the same timeframe, stable versions of iOS 26.3 and macOS 26.3 are expected to land on eligible iPhone and Mac devices later this month. iPadOS 26.3, watchOS 26.3 and tvOS 26.3 are also expected to be released, with the iOS update reportedly focusing on improvements to RCS messaging with Android devices.

Key RC details

• Release candidate iOS 26.3 and iPadOS 26.3 seeded to developers for testing
• Two new SoC models named T6051 and T6052 tied to H17C and H17D
• H17C is associated with M5 Max; H17D with M5 Ultra
• No references to T6050 or H17S in the RC, raising questions about the M5 Pro presence
• Launch window for updated MacBook Pro models in February or March 2026; M5 Ultra Mac Studio rumored
• Stable iOS 26.3 and macOS 26.3 expected later this month, with iPadOS 26.3, watchOS 26.3 and tvOS 26.3 likely to follow

These developments are based on beta-test notes and external reporting. Apple has not issued an official comment on the M5 lineup or the exact launch schedule.