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

iOS 26

6 New Things Your iPhone Can Do in iOS 26.1

Wednesday October 29, 2025 4:22 am PDT by
Apple is about to drop iOS 26.1, the first major point release since iOS 26 was rolled out in September, and there are at least six notable changes and improvements to look forward to. We've rounded them up below. Apple has already provided developers and public beta testers with the release candidate version of iOS 26.1, which means Apple will likely roll out the update to all compatible...
ios 26 1 slide to stop

iOS 26.1 Brings Back 2007 Feature in New Way

Friday October 31, 2025 1:40 pm PDT by
The upcoming iOS 26.1 update includes a small but helpful change for iPhones, and it could prevent you from running late to something important. Specifically, when an alarm goes off in the Clock app, there is a new "slide to stop" control on the screen for turning off the alarm. On previous iOS 26 versions, there is simply a large "stop" button, which could be accidentally tapped. The new ...
iOS 26

iOS 26.1 Coming Soon: New Features for Your iPhone and Release Date

Monday October 27, 2025 7:55 am PDT by
The upcoming iOS 26.1 update includes a handful of new features and changes for iPhones, including a toggle for changing the appearance of the Liquid Glass design, "slide to stop" for alarms in the Clock app, and more. Below, we outline key details about iOS 26.1. Release Date Given that Apple has yet to seed an iOS 26.1 Release Candidate, which is typically the final beta version, the...
iPhone 17 Pro Cosmic Orange

8 Reasons to Wait for Next Year's iPhone 18 Pro

Thursday October 30, 2025 4:42 am PDT by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...
M5 MacBook Pro

Waiting for New Macs? Apple Just Shared Bad News

Friday October 31, 2025 7:32 am PDT by
Apple has just given a strong indication that it will not be releasing any additional new Macs for the remainder of the year. Apple's CFO Kevan Parekh dropped the hint during the company's earnings call on Thursday:On Mac, keep in mind, we expect to face a very difficult compare against the M4 MacBook Pro, Mac mini, and iMac launches in the year-ago quarter.Parekh essentially gave a heads up ...
maxresdefault

Apple TV 4K Could Still Launch Before 2025 Ends: All the Rumored Features

Monday October 27, 2025 4:51 pm PDT by
Apple is designing an updated version of the Apple TV 4K, and rumors suggest that it could come out sometime in the next couple of months. We're not expecting a major overhaul with design changes, but even a simple chip upgrade will bring major improvements to Apple's set-top box. Subscribe to the MacRumors YouTube channel for more videos. We've rounded up all the latest Apple TV rumors. ...
ipad mini 7 feature blue

OLED iPad Mini: Release Date, Pricing, and What to Expect

Wednesday October 29, 2025 7:13 am PDT by
Rumors are stoking excitement for the next-generation iPad mini that Apple is reportedly close to launching. So what should we expect from the successor to the iPad mini 7 that Apple released over a year ago? Read on to find out. Processor and Performance Apple is working on a next-generation version of the iPad mini (codename J510/J511) that features the A19 Pro chip, according to...
iOS 26

Apple Seeds iOS 26.1, iPadOS 26.1, and macOS Tahoe 26.1 Release Candidates

Tuesday October 28, 2025 1:07 pm PDT by
Apple today provided developers and public beta testers with the release candidate versions of upcoming iOS 26.1, iPadOS 26.1, macOS Tahoe 26.1, tvOS 26.1, watchOS 26.1, and visionOS 26.1 updates for testing purposes. The RCs betas come a week after Apple released the fourth betas. The new betas can be downloaded from the Settings app on a compatible device by going to General > Software...
apple tv hd

Apple Launched Its Big New Vision for TV 10 Years Ago Today

Thursday October 30, 2025 8:58 am PDT by
Apple launched the Apple TV HD, the Siri Remote, tvOS, and their accompanying App Store a decade ago today, marking a major overhaul of the device. The new vision for the Apple TV was unveiled on September 9, 2015 during Apple's "Hey Siri" event in San Francisco, where CEO Tim Cook introduced the device with the statement, "The future of TV is apps." The announcement represented a major...

Top Rated Comments

Darth Tulhu Avatar
83 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
83 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
83 months ago
This machine is a day-one purchase for me. I really can't wait.
Score: 6 Votes (Like | Disagree)
Zdigital2015 Avatar
83 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
83 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
83 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)