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macOS Catalina Brings Back Expansion Slot Utility App Ahead of Mac Pro Launch

macOS Catalina, currently available to developers and public beta testers in a beta capacity, revives the defunct Expansion Slot Utility app ahead of the launch of the Mac Pro.

The Expansion Slot Utility app is designed for managing and configuring PCI cards, and its return is clearly meant for the Mac Pro, which has a total of eight PCIe expansion slots that Mac users can work with.


The Expansion Slot Utility app was discontinued years ago following the launch of the 2008 Mac Pro but the new 2.0 version is back for the modular Mac Pro.




Signs of the Expansion Slot Utility app are hidden in the second macOS Catalina beta, and when the Mac Pro becomes available at some point this fall, Mac Pro users will be able to take advantage of the utility.

Related Roundup: Mac Pro
Buyer's Guide: Mac Pro (Don't Buy)


Top Rated Comments

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11 weeks ago
Damn you Apple for pricing this thing out of my budget.

I love you Apple for building this thing and I want it bad.

Such is the war inside my head. The conflict. I am a Sith Lord after all. :p
Rating: 12 Votes
11 weeks ago

I've been using Macs for 2 decades now, never heard of this utility, tried to search on Youtube, nothing, it's says it's for configuring PCI cards, can someone tell me what to configure, I thought they were plug and play on a mac (after installing kexts).



The screenshots show it all. It's for allocating bandwidth. Seeing if your cards are getting the bandwidth they need, and managing what slots get how much bandwidth to the CPU/chipset.
It's very cool it can even be adjusted like this.
Rating: 8 Votes
11 weeks ago
This machine is a day-one purchase for me. I really can't wait.
Rating: 6 Votes
11 weeks ago

I think the real baffling part is that you associate piracy with Hackintoshes. How does that work?

And I don't understand how you think Apple takes a financial hit when people build Hackintoshes. Next you'll be telling me that building your own Windows PC, or buying one, is a hit on Apple


Someone using macOS on non-Apple hardware is a clear violation of Apple's EULA, no matter how noble some thinks the cause.

People not buying a Mac, but instead building a PC and then installing macOS on it means that a potential sale of an Apple computer is lost.

Apple does not sell a license for its operating system for use on a PC the way that Microsoft does with Windows, that's the difference.
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I guess this confirms for sure (as if it wasn't already obvious) that the new Mac Pro will not be able to run Mojave (and therefore legacy 32-bit apps).


Nope, of course that won't stop someone from trying to run some old 32-bit app that has never been updated, been abandoned or a newer version exists (with associated upgrade cost or subscription fee).

EDIT: And then getting on this site to bitch about it as if it is Apple personally screwing them over, but I digress.
Rating: 5 Votes
11 weeks ago

I've been using Macs for 2 decades now, never heard of this utility, tried to search on Youtube, nothing, it's says it's for configuring PCI cards, can someone tell me what to configure, I thought they were plug and play on a mac (after installing kexts).


It's something you don't want. Legacy Mac Pros didn't have enough PCI-E lanes for all the slots. The old utility allowed you to switch between different lane configurations, for example x16/x8/x1/x1 if you had one graphics card, or x8/x8/x8/x1 if you had 3. This was common on PCs too, sometimes software but other times via a bunch of jumpers.
Rating: 4 Votes
11 weeks ago

Damn you Apple for pricing this thing out of my budget.

I love you Apple for building this thing and I want it bad.

Such is the war inside my head. The conflict. I am a Sith Lord after all. :p


Exactly... I have the money but don't need it. I could justify buying the Mac Pro previously even though I didn't need it, but I am having a hard time doing that now. The only thing that might make me purchase this thing is if the upgrades aren't ridiculous, but that wouldn't be very apple like... the base config for that price is just ridiculous.
Rating: 4 Votes
11 weeks ago

Maybe the ability to use nvidia rtx cards etc?


No, no. This tool has nothing to do with support for the cards you might plug in. That's a matter of drivers.
This tool is just about bandwidth distribution. Making sure the cards you do plug in have the bandwidth to run at their best speeds.

But frankly I don't see this helping Hackintoshes at all. This is a tool that communicates with hardware, specifically the motherboard and its PCIe lane distribution chips. I find it hard to believe it'd work with any motherboard out there. Most motherboards don't even support distributing PCIe bandwidth like this, and have the lanes fixed to certain slots.
Rating: 4 Votes
11 weeks ago
This should be handy for Hackintosh users! (Providing they're emulating the new Mac Pro)
Rating: 3 Votes
11 weeks ago
I get it. I can not justify the MP when my Hackintosh does more for less.
Having resources to buy something is not a mandate to waste same.
Better luck next time Apple.

License the OS. That would be “thinking different”.

Support NVIDIA and stop being so predictable.

The more Apple becomes like it did before Jobs came back, the more I think of Apple Park like the colleseum in Rome. A round sign that things are ending.
Rating: 3 Votes
11 weeks ago

I have been wondering if the Afterburner FPGA will be opened up for other usage.



Well AMD is working hard on ROCm. Or may be it should be Google working more on Tensorflow ROCm rather than focusing on CUDA?

I think ROCm is close, very close. But like everything when the work is 80% done and you thought the 20% is going to be easy, that 20% normally takes the same amount of time as the first 80%. People are aware of the CUDA lock in, and once AMD reaches the point of good enough, more people will switch and more people will help with ROCm

And needless to say Apple by themselves are also heavy user of Machine Learning.


Not being an expert on the intricacies of ML, my take is that Apple does not want NVIDIA to subvert or be able to exert any influence or control over the on device ML that any A11 or A12 equipped hardware can perform. Apple wants its devs using CoreML and writing native for its iOS devices, not letting CUDA get its foot in the door on the Mac side and then developers focus on the largest marketshare or think they can forgo CoreML. It would give NVIDIA an even bigger presence in the market and Apple does not want another company dictating this technology to them as they use it to their competitive advantage when adding features to the iPhone, especially with photo processing. Just my 2¢.
Rating: 3 Votes

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