Popular Mechanics (South Africa)
The I.T. Guy:
The stealth cooling system that powers the Mac Pro.
AS I’M NEITHER a Pixar employee nor a YouTuber, I don’t require a Mac Pro. Even the base model is complete overkill. Spend a few (tens of) thousands of rands on options, and you can get a 28-core CPU, and 1.5 terabytes of DDR4 memory. Those numbers imply a level of engineering I look at from a distance and say: ‘That’s awesome.’
Same as with almost any product, industry-top performance like that creates heat that needs to be kept away from vital components. Most high-grade PCs do this with fans or pump-driven water systems. But those can be loud, and if you have used a Mac in the last few years, you’ve noticed that nearsilent operation is a non-negotiable design requirement. This meant that the Pro’s creators had to find creative ways to exploit the laws of thermodynamics.
A team led by Chris Ligtenberg, Apple engineer and pilot, handled the fans. ‘They’re still dynamically balanced, but they’re actually randomised in terms of their
BPF [blade pass frequency],’ he says. ‘So you don’t get huge harmonics that tend to be super annoying.’ That means that audible but pleasantly pitched fan sounds can be less noticeable than a measurably quieter system. The randomisation technique he’s describing came from research in car tyres. ‘There’s a bit of maths behind it, but you can create broadband noise instead of total noise with that technique,’ he says.
The fans supplement an aluminium case, which has two grids of precision holes, likely the most ornate examples of passive cooling ever. Passive cooling structures absorb heat, away from vital components, then dissipate that energy into the air. The more exposed surface area, the better it works. Next time you see a motorcycle, look around the engine for a bunch of thin metal fins. That busy design creates a lot of surface area for a given volume of space.
Fins need to stay in one position to keep air flowing through their channels. But the Pro Display
XDR monitor had to be able to rotate 90°, which would have trapped air. So Apple designed the holes. ‘We wanted free flow through the channels, no matter the orientation,’ says John Ternus, head of the Pro and Pro Display’s development. ‘[The pattern] gives us a lot of surface area, which is hugely beneficial.’
We can credit Apple’s ubiquity, at least in part, to that high level of detail obsession. It’s a controversial company. But however you feel about its practices or products, few other places would take temperature regulation this far.