a look at power on the new M1 Max: part 1

preface

When Apple announced the new 14″ and 16″ MacBook Pros, it was a defining moment in computing. For the first time in recent history high-performance ARM-based systems are widely available to consumers.

Apple released their first ARM-based systems running a desktop OS late last year, the first Macs with ‘Apple Silicon’. The M1 chip featured 8 cores with 4 high-performance cores and 4 efficiency cores, up to 16GB of LPDDR4X memory and up to 8 GPU cores.

The M1 chip demonstrated Apple’s ability to deliver on desktop-class performance and was generally met with praise, especially when considering the advantages the power efficiency brought to the table when comparing to similar laptops.

Apple was able to deliver a fanless design in the case of the MacBook Air, whilst keeping the power envelope low and performance way in excess of what an Intel or AMD based laptop could within the same thermal constraints. The result was a laptop with incredible battery life, great CPU performance and even sufficient GPU power to position the new entry-level Macs as an ideal system for the vast majority of users.

The M1 chip was not without its limitations though, for example, the ability to use only a single external display was a point of contention for many prospective users looking to replace older Intel-based Macs.

Enter the M1 Pro and M1 Max.

scaled up designs

The M1 Pro and M1 Max are the chips featured in the new MacBook Pros. They are a continuation of the Apple Silicon line-up, and Apple’s answer to the ‘Pro’ audience. They come in a myriad of configurations, binned on CPU and GPU core counts and also with 16, 32 or 64GB of LPDDR5 memory in a massive SoC (system on a chip).

That is a massive SoC, 57 billion transistors. (Source: Apple)

Unlike the entry-level M1 counterpart, these chips feature up to 8 high-performance cores with an additional 2 efficiency cores, and up to 32 GPU cores all on a massive memory subsystem with a theoretical 408GB/s throughput (512-bit LPDDR5-6400) in the case of the M1 Max.

This kind of configuration is significant because typically only high-end discrete GPUs have access to this kind of memory bandwidth, yet it is shared on a common fabric with the CPU cores able to access a substantial amount of that bandwidth. Some testing shows a single thread able to utilize in excess of 100GB/s bandwidth, unheard of in x86 laptop systems.

What was most interesting for me was the inclusion of all available chip configurations on both the 14″ and 16″ models. The highest end configuration with M1 Max and 32 GPU cores could be built-to-order for the 14-inch model and this prompted me to wonder about thermals and power constraints. Despite the fantastic efficiency of these chips, the M1 Max is a big chip, with 57 billion transistors on a 5nm process.

Could the 14″ model offer similar performance to the 16″ counterpart when configured with this 32-core option? Try as I might, I couldn’t find much discussion around it so I decided to investigate.

the epic experience

Self reported package power of less than 1W at idle on the M1 Max

I ordered the highest tier standard configuration of the 16″ MacBook Pro on launch. This came with the M1 Max and 32GB of memory as shown in the screenshots above.

After a week with it I’ve come to terms with the behaviour, peeking at powermetrics as often as I could doing various tasks. Given the larger chassis with naturally greater thermal headroom and 140W power adapter, I was still surprised to see package power sit below 1W when idle. This is honestly fantastic, and I recorded some figures doing various tasks for comparison later.

ActivityDRAM PwrCPU PwrGPU PwrPackage Pwr
Idle0.24 W0.05 W0.01 W0.64 W
4K YouTube0.47 W0.13 W0.06 W1.45 W
Cinebench R231.64 W19.94 W0.01 W24.96 W
Metro: Exodus5.50 W8.95 W35.29 W61.28 W
CB23 (6T) plus
Metro: Exodus
5.30 W24.11 W33.02 W74.03 W
Metro: Exodus
Low Power Mode
4.07 W5.99 W11.77 W30.30 W
Self-reported power metrics doing various activities on an 16″ MBP with M1 Max

Here we see a pretty large spread of reported power figures, from less than a watt at idle, to 74 watts package power when running Cinebench R23 with 6 threads and Metro Exodus (1600p/Ultra), the latter being the most power draw I could achieve consistently with any workload.

Interestingly, when enabling ‘Low Power’ in the Battery section of system preferences, package power never exceeds much past 30W, which hints towards the chip maintaining a power target of 30W when low power mode is enabled and the system is unplugged. This 30W limit was not seen with the power connected, even with Low Power Mode enabled.

When you include a Cinebench R23 run in the background, the package power climbs to 74 W. This is the most I’ve seen with any workload on the 16″ MacBook Pro, I had to limit CB23 to 6 rendering threads so that Metro: Exodus would consistently produce a smooth framerate, yielding this peak load. The fans were audible, but not uncomfortable at this load.

Metro: Exodus ran smoothly at 2560×1600 (Ultra) reporting 61W package power.

interpreting results

I’m fairly confident based on my usage and testing that there’s likely few circumstances, bandwidth aside, where the M1 Pro or M1 Max in either chassis will be CPU constrained. I can’t get the package to pull more than 30W in any situation where the task at hand is CPU-focused. Given my Intel-based 13″ MacBook Pro can sustain close to 35W at full tilt, this shouldn’t be a problem for either of the new designs.

Running Metro: Exodus on Low Power Mode with the power unplugged.

Additionally, discovering that Low Power Mode seems to limit power draw to 30W on battery was a bonus, it will be interesting to see whether this behaviour is the same on the 14″, or whether the target wattage differs.

Where it does look less convincing is GPU-centric tasks, 74 watts is a lot for a 14″ chassis, even with Apple’s quoted 50% improvements to air flow and increased chassis depth, I very much doubt it’ll be able to sustain that kind of load, at least not without the fans screaming in agony. Even taking a step back and appreciating a more realistic 60W load, as tends to be the norm when I play games (Metro, Witcher 3, FFXIV etc…) – it does leave me wondering whether the 14″ M1 Max can really keep up.

will physics win?

So as I’ve established, I’m sceptical that the 14″ MacBook Pro will be able to maintain this level of performance, I went to reddit to ask about differences between the devices and one user noted power draws and clock speeds were lower, also suggesting the 16″ is the ‘epic’ experience, the 14″ being the ‘perfect’ experience.

I have a 14″ M1 Max equipped device with 64GB of memory on the way which Apple estimates will arrive before December. When the device comes, I’ll run the same suite of tests and see how that holds out.

Honestly – the 16″ is a nice laptop and the screen is gorgeous, but on more than one occasion I’ve found myself reaching for my 2020 Intel-based 13″ MacBook Pro when on the move as I loathe to carry a bag big enough to lug around the 16″.

Thanks for reading!

By Lily Hall

25yo software engineer living in the UK and the creator of nyaa.sh / all views are my own

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