Mac Studio with M1 Ultra is heavier because of heat & material choices

Internals of the new Mac Studio

The Mac Studio with an M1 Ultra chip is nearly two pounds heavier than the one with an M1 Max because of thermal differences between the two variants.

After the Mac Studio debuted on Tuesday, some people vocally wondered by the M1 Ultra version was heavier by about a full kilogram, or around two pounds. The M1 Max model weights 5.9 pounds, while the M1 Ultra version weighs in at 7.9 pounds.

While the M1 Ultra is basically two M1 Max chips stitched together, that wouldn't explain such a difference in weight. The Verge reached out to Apple and got an answer.

According to Apple, both versions of the Mac Studio use the same 370W power supply. The additional weight on the M1 Ultra version is because of a "larger copper thermal module." The M1 Max Mac Studio, on the other hand, has an aluminum heatsink instead.

In general, copper is a better heatsink material of its density than aluminum. While aluminum has about 30% the density of copper, aluminum also has about 60% of the conductivity that copper does given the same basic construction of the heat sink.

Aluminum is significantly less expensive than copper, though. For the same mass, copper costs about three times as much.

The response from Apple also revealed that the M1 Ultra version of the Mac Studio uses the same power supply as the lower-tier variant.

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14 Comments

netrox

said about 2 years ago

Given the large price difference between M1 Max and M1 Ultra, this makes sense.

flydog

said about 2 years ago

netrox said:

Given the large price difference between M1 Max and M1 Ultra, this makes sense.

What? Even if the entire 2 lbs was copper heatsink, the difference in material cost is at most $5 if Apple paid retail for copper.

dk49

said about 2 years ago

Why does this need 370W power supply if its peak performance can be achieved at 100W?

mpantone

said about 2 years ago

dk49 said:

Why doesn't this need 370W power supply if its peak performance can be achieved at 100W?

PC power supplies are typically the most efficient between oh, let's say 30-70% load (about 110-260 watts for this unit).

In the Mac Studio the same power supply supports both the M1 Max and the M1 Ultra, the latter which will draw more power. Don't forget that there are different GPU configurations (number of cores). There are also other transistors that draw power both in the package (e.g., unified memory, the interconnect) as well as elsewhere in system (e.g., NAND flash storage, connectivity, Bluetooth and wireless radios, etc.). And there are the mechanical components (two blowers) that also draw current.

This PSU is specced out to support the maximum configuration (M1 Ultra, 128GB memory, maxed GPU, 8TB SSD, all six TB4 ports running at full speed) not the entry-level offering or something in the middle. Unlike a typical PC chassis, you can't just swap out a 650W ATX PSU with a 1200W replacement on a Mac Studio.

From a cost and supply standpoint, it's probably easier for Apple to simply design one PSU rather than have multiple PSUs with different capacities. I'm sure they tried a bunch of different PSUs while prototyping.

Consumer semiconductors also have a sweet spot. The performance-to-watt curve typically isn't a straight line. At the top end of the curve, you can increase the power but only reap modest gains with today's silicon. Gone are the days of overclocking CPUs and GPUs for massive gains. Today's chip designers are putting most of that headroom in the chip's boost design. There's very little improvement to be gained from Joe Consumer.

PSUs lose efficiency at really low loads and really high loads. If a hypothetical system maxes out at 198 W sustained, you don't want to put in a 200 W PSU. That's a 99% load; you lose efficiency and there's no headroom for short term boosts of power.

godofbiscuits

said about 2 years ago

flydog said:

netrox said:

Given the large price difference between M1 Max and M1 Ultra, this makes sense.

What? Even if the entire 2 lbs was copper heatsink, the difference in material cost is at most $5 if Apple paid retail for copper.

The IP for the Apple Silicon won't be paid down for a long, long time. Apple's only now getting around to being able to put an A13 in a monitor.