Turning off M1 Max GPU cores when idle?

[project_2501]

Several people have found the M1 Max consumes more battery even when idle. Apple seems to have confirmed this.

The result is that an M1 Max laptop will run out of battery quicker than a M1 pro even when idle (not running GPU intensive tasks).

Why didn't Apple "turn off" the GPU cores when the workload doesn't require it?

This idea is in fact part of the ARM approach in recent years with bigger or higher performance cores sat next to lighter lower power cores - see the ARM Big.Little architecture from a few years ago. I thought this was the idea behind Apple Silicon's performance and normal cores?

 

[leman]

Why didn't Apple "turn off" the GPU cores when the workload doesn't require it?

They certainly do turn them off. Unfortunately, it's not just about the GPU. The memory interface is wider and the chip fabric is larger, so even with advanced power gating the Max will still have a higher idle overhead. And even a very small difference here can already make a huge impact.

 

[cp1160]

They certainly do turn them off. Unfortunately, it's not just about the GPU. The memory interface is wider and the chip fabric is larger, so even with advanced power gating the Max will still have a higher idle overhead. And even a very small difference here can already make a huge impact.

Expressing my ignorance on the impact...how much more power greedy is the chip when having the lightest load and what would the impact on battery life be all other things as equal as they could be?

 

[leman]

Expressing my ignorance on the impact...how much more power greedy is the chip when having the lightest load and what would the impact on battery life be all other things as equal as they could be?

Can't answer this question without having access to the data. But this can be measured. In fact, measurements I've seen suggest that M1 Pro and M1 Max are not that different in their baseline power consumption. But I suspect that Max will have higher aggregate power consumption when it has to fire up its memory bus.

And the impact is quite big. Let's say that M1 Pro has aggregate idle power consumption of 0.5 watt and M1 Max of 1 watt (these are both ridiculous slow). Taking 14" battery capacity (70W) and assuming that the rest of the system (display etc.) draws ~4W, this already translates to 1.5 hour difference in battery life (approx 15.5 hours vs. 14 hours)...

 

[zarathu]

I have a late 2013 intel MBP that turns off its processors if the voltage gets too low. This saves battery. Of. course the side effect is that it also shuts down the computer.

I have a piece of software on it that keeps them all awake, which reduces battery. The side effect of this is that instead of Geek benchmarking at 2900 for multi, the mac benchmarks at 3600.

You win some, you lose some.