macOS 27.2 Beta 2 - High Power Mode broken on MacBook Pro 14" M5 Pro (Mac17,9)

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Subject: Hard SMC and Kernel bug on 14" MacBook Pro M5 Pro (Mac17,9) in Build 26B5091g - High Power Mode completely unresponsive

Hello CoreOS and Apple Silicon Performance Engineering Teams,

I am writing to report a severe, reproducible system-level regression regarding High Power Mode and SMC power distribution on the new 14-inch MacBook Pro with the M5 Pro chip (Model Identifier: Mac17,9), currently running macOS 27.2 Beta 2 (Build 26B5091g).

The issue prevents the M5 Pro hardware from scaling its cooling and power envelope correctly, rendering High Power Mode completely broken regardless of the power source (tested with both official 96W and 140W Apple power adapters).

Key technical diagnostic findings from my device:

Kernel vs UI State Mismatch: Running pmset -g via Terminal returns powermode 2, proving that the kernel registers High Power Mode as active. However, the System Information profile reader (Hardware -> Power) shows a direct conflict: "High Power Mode: No" and "Low Power Mode: Yes" (Режим энергосбережения: Да).
Unresponsive SMC & Fan Curves: The cooling hardware remains completely unresponsive to the high-performance toggle. The fans fail to engage the pre-emptive 4500-5000 RPM cooling curve under heavy compute or gaming loads, remaining locked in the silent "Automatic" profile, which causes artificial thermal constraints.
Powermetrics Telemetry Anomalies: A raw powermetrics trace captured during this state reveals a severe thread management bug:
- The P0-Cluster (High-Performance cores) shows a down residency of 98.88%, meaning the heavy performance cores are effectively kept asleep by the OS governor during high-power configuration.
- Combined Power (CPU + GPU + ANE) drops to a mere 429 mW.
- The thermal sampler entirely fails to pull hardware RPM telemetry from the SMC fan loops, providing only a generic "Current pressure level: Nominal" string.

This profile behavior confirms that the macOS 27.2 power governor layer is suffering from a hard breakdown in SMC communication specific to the J614/Mac17,9 platform. The operating system handles the software flag but fails to pass the physical instruction downstream to the hardware control registers.

Please prioritize this issue for the next macOS 27.2 beta cycle to ensure full thermal and compute optimization for the M5 Pro architecture prior to the final public release.

I have attached the complete sysdiagnose archive, terminal configuration text files, and raw powermetrics logs.

Thank you for your dedication to Apple Silicon optimization. FB24929043

Answered by DTS Engineer in 906928022

Thanks for filing FB24929043. That’s the right path for feedback like this.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Answer 1

Heartbleed OP

2d

Accepted Answer

fan_smc_metrics.txt

1_hardware_id.txt

2_power_assertions.txt

3_smc_battery_raw.txt

4_kernel_power_events.txt

Answer 2

DTS Engineer OP

Apple

1d

Recommended

Thanks for filing FB24929043. That’s the right path for feedback like this.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Answer 3

DTS Engineer OP

Apple

1d

A few minor notes:

However, the System Information profile reader (Hardware -> Power) shows a direct conflict: "High Power Mode: No" and "Low Power Mode: Yes" (Режим энергосбережения: Да).

I understand the confusion, but what's actually going on here is that we're using the same terminology to mean different things in different places:

"pmset -g" -> This is telling you how the machine is configured, meaning whether or not the machine is configured to allow the higher fan speed of High Power Mode.
"System Information" -> This is telling you what the machine’s current state is at that particular moment in time.

...so it's normal for an idle machine with High Power Mode enabled to be in Low Power Mode. It's not doing anything so the fans aren't running.

Finally, a clarification here:

Unresponsive SMC & Fan Curves: The cooling hardware remains completely unresponsive to the high-performance toggle.

Despite its name, High Power Mode is purely a thermal setting, as all it actually does is raise the limit on how fast the system will allow the fan to run. Under some conditions that higher fan speed will allow some additional performance, but if external conditions allow the machine to stay cool enough, it's entirely possible for it to max out all CPUs without running the fans faster.

__
Kevin Elliott
DTS Engineer, CoreOS/Hardware