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.

macprointernalsnomodules
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 (Neutral)
Related Forum: Mac Pro

Popular Stories

iPhone 17 Pro 3 4ths Perspective Aluminum Camera Module 1

New iPhone 17 Pro Details: Brighter Display, Best Battery Life, and More

Wednesday September 3, 2025 5:33 am PDT by
Apple's iPhone 17 Pro and iPhone 17 Pro Max models will feature a number of significant display, thermal, and battery improvements, according to new late-stage rumors. According to the Weibo leaker known as "Instant Digital," the iPhone 17 Pro models will feature displays with higher brightness, making it more suitable for use in direct sunlight for prolonged periods. The iPhone 16 Pro and...
iPhone 17 Pro Iridescent Feature 2

iPhone 17 Pro Clear Case Leak Reveals Three Key Changes

Sunday August 31, 2025 1:26 pm PDT by
Apple is expected to unveil the iPhone 17 series on Tuesday, September 9, and last-minute rumors about the devices continue to surface. The latest info comes from a leaker known as Majin Bu, who has shared alleged images of Apple's Clear Case for the iPhone 17 Pro and Pro Max, or at least replicas. Image Credit: @MajinBuOfficial The images show three alleged changes compared to Apple's iP...
iPhone 17 Pro Iridescent Feature 2

iPhone 17 and iPhone 17 Pro Prices Estimated Ahead of Apple Event Next Week

Tuesday September 2, 2025 1:50 pm PDT by
Just one week before Apple is expected to unveil the iPhone 17 series, an analyst has shared new price estimates for the devices. Here are J.P. Morgan analyst Samik Chatterjee's price estimates for the iPhone 17 series in the United States, according to 9to5Mac: Model Starting Price Model Starting Price Change iPhone 16 $799 iPhone 17 ...
iphone 16 pro ghost hand

iPhone 17 Pro: 5 Reasons Not to Upgrade This Year

Monday September 1, 2025 4:35 am PDT by
Apple will launch its new iPhone 17 series this month, and the iPhone 17 Pro models are expected to get a new design for the rear casing and the camera area. But more significant changes to the lineup are not expected until next year, when the iPhone 18 models arrive. If you're thinking of trading in your iPhone for this year's latest, consider the following features rumored to be coming to...
iPhone 17 Pro Dark Blue and Orange

iPhone 17 Release Date, Pre-Orders, and What to Expect

Thursday August 28, 2025 4:08 am PDT by
An iPhone 17 announcement is a dead cert for September 2025 – Apple has already sent out invites for an "Awe dropping" event on Tuesday, September 9 at the Apple Park campus in Cupertino, California. The timing follows Apple's trend of introducing new iPhone models annually in the fall. At the event, Apple is expected to unveil its new-generation iPhone 17, an all-new ultra-thin iPhone 17...
Apple Watch Ultra 2 Complications

Apple Watch Ultra 3 Coming Next Week: Eight Reasons to Upgrade

Thursday September 4, 2025 7:38 am PDT by
We're only days away from Apple's "Awe dropping" fall event scheduled to take place on Tuesday, September 9 – and along with the new iPhone 17 series, we're going to get a new version of the Apple Watch Ultra for the first time since 2023. By the time the Ultra 3 is unveiled, it will have been two years since the previous model arrived. The intervening period has left plenty of room for...

Top Rated Comments

Darth Tulhu Avatar
81 months 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
Score: 12 Votes (Like | Disagree)
casperes1996 Avatar
81 months 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.
Score: 8 Votes (Like | Disagree)
BarredOwl Avatar
81 months ago
This machine is a day-one purchase for me. I really can't wait.
Score: 6 Votes (Like | Disagree)
Zdigital2015 Avatar
81 months 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.
[doublepost=1562017421][/doublepost]
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.
Score: 5 Votes (Like | Disagree)
jameslmoser Avatar
81 months 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.
Score: 4 Votes (Like | Disagree)
casperes1996 Avatar
81 months 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.
Score: 4 Votes (Like | Disagree)