Friday, Dec 10, 2021, 13:50 Mac: Hardware

M1 Max and M1 Pro: Faster with Power Supply than in Battery Mode?

MacBook Pro 14" and MacBook Pro 16" are characterized by a good stamina - in terms of battery life. According to Apple's official information, the new notebooks from Cupertino can run for up to 17 or even 21 hours on one battery charge before they have to be recharged. They also have a "low power mode", which reduces the performance a bit and thus extends the battery runtime a bit. However, many owners also use their devices regularly with the power adapter connected.

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Test with performance cores and efficiency cores
Developer Howard Oakley now examined how power supply and operating mode affect performance. For the test, the result of which he published on his blog The Eclectic Light Company, he used a series of specially created processes, which were exclusively processed by the CPU cores. The GPU parts of Apple's in-house chips were not used. The four apps he used included a floating point calculation written in assembly language and an integer multiplication. He executed these in parallel on several cores, specifically on both the two efficiency cores (E-Core, "Icestorm") and the eight performance cores (P-Core, "Firestorm").

Performance identical in mains and battery operation
To Oakley's surprise, the two E-Cores always worked at the same speed in all three tests, so they delivered the identical performance in mains and battery mode with both activated and deactivated low power mode. Thus, operating mode and power supply do not affect these cores in any way. This is different for the P-cores: Although they did not show any difference between mains and battery operation with deactivated Low Power Mode, turning on the energy-saving mode caused a noticeable reduction in CPU performance. The MacBook Pro decreased the processor's clock frequency from the normal 3.2 gigahertz to 2.8 gigahertz, which lowered the performance to 88 percent. The result was almost identical in all four apps used for the measurement.

Low Power Mode reduces performance only slightly
Oakley explicitly points out that its results only reflect the influence of Low Power Mode on the pure computing performance of the M1 Pro and M1 Max. The performance of other components such as GPU, RAM and SSD can therefore definitely be additionally influenced by the type of power supply or the Low Power Mode. However, according to Oakley, the performance reduction of the P-cores, which are responsible for the execution of apps, the user interface, and time-critical processes, should only be noticed by the user in the form of a slightly reduced work speed.

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