Inside the new Mac mini: Does Apple's M1 architecture really leave Intel behind?

While the same M1 chip is coming out in the MacBook Air, MacBook Pro, and Mac mini, the design of the mini gives us some forensic clues about how the M1 chip might be designed.
Written by David Gewirtz, Senior Contributing Editor

The new M1 Mac mini is... hmm. It's not a slam dunk, but neither is it a complete WTF. It's ready enough for prime time for some tasks, and carries the Apple Silicon question mark for other tasks. It's worth buying, but not for everyone or every workload.

Chipset concerns

No, we're not talking about the money supply or a tank (other common uses of "M1"). Instead, our subject is the new CPU Apple introduced at this week's Apple Event. The M1 is an all-Apple design based on their mobile chips and the Arm architecture. And, yeah, it has potential.

With high-performance and efficiency workload cores, with a deep commitment to on-silicon machine learning, and with an onboard GPU that shows some potential, this could be an architecture that leaves Intel behind.

Just not so much yet. I talked previously about all the things that can go wrong in an architecture lift-and-shift. I also spoke about Apple's impressive track record of previous processor replacements in Macs. All that remains true after the Apple announcement.

Big questions remain about how individual programs perform on the new M1. Some, like the Apple-developed juggernaut Final Cut Pro X, should perform exceptionally well.

Others, like Photoshop and Fusion 360 - both mentioned in the Apple event - will either be ported to the new processor or be emulated. Performance on these, if mediocre now in Intel Rosetta 2 emulation, will undoubted get substantially better as their developers release updates.

Virtual machines like Fusion, Parallels, and VirtualBox remain up in the air. Parallels is recruiting testers for its fully emulated version of the Intel instruction set on the M1. If you use a Mac and you rely on Windows in virtualization, you'll want to skip the M1 version, at least until the VM vendors finish their ports.

All of this is common across the three machines that Apple announced. Let's look specifically at the Mac mini.

The 2020 M1 Mac mini

After owning the 2018 Mac mini redesign, the new M1 is a bit of a letdown. We knew we'd probably see an Apple Silicon Mac mini early, simply because the developer kits released this summer were Mac mini-based.

The Mac mini is a very versatile form factor, especially for those working at desks. It's definitely my favorite. I own five, ranging from 2011 to 2018.

But the 2020 Mac mini takes a step backward from the Intel-based 2018 model.

It loses two Thunderbolt 3 ports. The 2018 Intel model came with four Thunderbolt 3 ports and two USB-A ports. The 2020 M1 model keeps the USB-A ports, but provides only two Thunderbolt 3 ports.

It also loses the ability to support 10Gb Ethernet. Yes, granted the 10Gb feature was an optional upgrade to the 2018 machine, but that upgrade is not available for the 2020 M1 machine.

Another major issue is how the M1 appears to handle memory. RAM doesn't appear to be delivered via a separate module. It looks like the M1 comes out of the fab with not only in-chip video, but in-chip RAM.

To be clear, in-chip RAM could well provide a strong performance boost. Bits that have to travel in and out of two separate chips will have a much larger propagation delay than bits that have to travel inside a single chip. So expect RAM performance to increase substantially.

But the 2020 M1 ships with only 8GB or 16GB. Honestly, in 2020, even fabricating an 8GB chip seems parsimonious. But there could be yield issues with the M1. It's possible (probable, even) that the 8GB and 16GB come from the same chip die. I'm wondering if the ones where all the RAM bits work go into 16GB machines and the ones that have failures go into the 8GB machines with their failed bits blocked by the OS or onboard controllers.

Contrast this minimal RAM footprint with the spacious 2018 Intel Mac mini. That had capacity up to 64GB.

What these limitations may imply about the M1

Apple tends to update its chips annually, and we can be pretty confident the M1 will be replaced by an M2 next year.

While Apple has lauded the M1's performance, note that they have substantially restricted the amount of data that has to travel in and out the M1's ports. Each Thunderbolt 3 port can max out at 40Gb/s. The 10 Gb Ethernet port can theoretically max out at 10Gb, while the 1Gb maxes out at a tenth of that.

When we combine the non-HDMI data ports on the 2018 Mac mini, we get this:

  • (2) USB 3.1 at 5Gb/s each for a total of 10Gb/s
  • (1) Ethernet port maxed at 10Gb/s
  • (4) Thunderbolt 3 ports at 40Gb/s for a total of 160Gb/s

All told, the 2018 Mac mini has a maximum theoretical transfer capability of 180Gb/s.

Now, contrast that with the 2020 M1 Mac mini:

  • (2) USB 3.1 at 5Gb/s each for a total of 10Gb/s
  • (1) Ethernet port maxed at 1Gb/s
  • (2) Thunderbolt 3 ports at 40Gb/s for a total of 80Gb/s

The 2020 M1 Mac mini has a maximum theoretical transfer capability of 81Gb/s, just over half the capability of the Intel 2018 version.

If you combine the super performance of the M1 along with the reduced data transfer capability and reduced RAM capacity (probably with less effective integrated circuit yields) it's reasonable to observe that:

  • The M1 might not yet be optimized for inter-module communication
  • The M1 might be having fab yield issues
  • The M1 may have sacrificed some transistors from port circuits to provide capacity for the additional machine learning cores (or some other part of the complex chip design)

I think it may well be a combination of all three. Apple has notoriously been anti-port so it makes sense that if they had to make a trade-off decision, they'd sacrifice connectivity.

All that is to say that "1" is a very lonely number and we can expect these first Apple Silicon Macs to be joined by M2 machines next year.

What about Intel? What should I buy?

We haven't gotten any early usage impressions from the new M1 machines. So it's kind of early to tell you from experience whether they are generally pretty good or not. That said, let's assume they rock.

Now, how do you decide?

If you're a relatively light user and don't use virtual machines, go for the M1 Mac mini. It will show improvement with every new OS release for years. It could well be a 10-year machine.

If you're a developer or want to get your hands on an M1 because you "wanna," then get the M1 Mac mini. At a starting price of $699, it's certainly priced low enough.

If you use Final Cut or Logic, definitely consider getting the M1 machine. This is the CPU and video footprint that Apple is likely have optimized strongly for workloads generated by these applications. I am incredibly curious to see how the new machines handle Final Cut.

But... if you're an extreme pro user who needs a lot of RAM, a lot of ports, and virtual machines to run other operating systems, you're going to want to buy the Intel Mac mini Apple still has on offer.

When you go to Apple's sales site, you'll initially only see an i5 Intel Mac mini. Apple used to list the various processor options side by side. Now, you have to select the i5 mini and choose the i7 processor. You can also buy overpriced RAM up to 64GB, but if you're even slightly handy, you might want to install extra RAM yourself and save a bit.

Yes, the Intel Mac mini will probably stop getting upgrades in a few years (as compared to, say, a decade), but if you need the capability, you need the capability.

So far, no Apple Silicon Mac can handle more than 16GB of RAM or provide a whole bunch of ports.

Wrap up

Right now, my main desktop is a maxed out 2018 Mac mini. I'm not only using all the ports, I'm also daisy-chaining all the Thunderbolt and USB ports. I probably have a dozen devices hooked up to that machine.

But other than my main machine, if one of my other Mac minis died, or I needed to add a new computer, I'd definitely consider the M1 version. For most uses, it should be pretty darn capable. And the price is certainly right.

But keep in mind that my main desktop needs more than 32GB RAM and that I use all four Thunderbolt ports. I also concurrently run Windows and Linux in multiple VMs. If I had to replicate that, I'd probably still stick with buying Intel for that workspace because I need all that capability, every day, now.

What are your thoughts? Are you planning on getting any of the M1 machines? What are you most excited about? What worries you?

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