Hub or dock for new M4 MacBook Air?

For your first question:

You're correct that 16GB is already a very capable amount of memory for the vast majority of everyday tasks — browsing, productivity, light photo or video editing, and even moderate app development or virtual machines. The unified memory architecture on Apple Silicon means 16GB on an M4 performs more efficiently than 16GB ever did on Intel.

With that said, 24GB can be a future-proofing move. If you foresee leaning into AI tools (like running local LLMs, heavy image generation models, or advanced data sets), or doing serious multitasking — say, working with Lightroom + Final Cut + Xcode + multiple Chrome tabs + virtualization — then that extra headroom can keep you from hitting swap. It also helps if you routinely use apps like Logic Pro or Final Cut Pro with large libraries and plugins. Otherwise, if your use case is similar to what you're doing now and you're not chasing the AI or media production edge, 16GB is absolutely fine for several years ahead.

For your second question:

If your peripheral needs are basic — a few USB-A devices, maybe Ethernet and HDMI — a USB-C hub is more than enough and keeps things simple and portable. Something like an Anker or Satechi hub with USB-A, Ethernet, HDMI, and pass-through power should do.

However, if you plan to treat your new Mac more like a desktop — docked at a desk with a display, wired internet, external drives, audio gear, etc. — then a Thunderbolt dock is a better long-term investment. It gives you more stable performance (especially with displays and storage), cleaner cable management, and power delivery. OWC, CalDigit, and Plugable all make excellent options.

For your third question:

No — at least not easily or natively. Apple dropped Target Display Mode support after the 2014 iMacs, and your 2017 Intel iMac doesn't support it. There's no built-in way to use that iMac as an external display for a new MacBook Air.

That said, there are third-party software workarounds like Luna Display (hardware dongle + app), Duet Display, or Sidecar-style apps that can run on both machines and stream the display over Thunderbolt or Wi-Fi. But keep in mind that these are never quite as responsive or color-accurate as a true external monitor.

If you think you’ll want a second screen often, it might be worth investing in a dedicated external monitor — there are excellent USB-C monitors that are sharp, color-accurate, and affordable.

johnzfoster wrote:

Hi,

I'm considering investing in a M4 MacBook Air (currently have Intel 2017 iMac 24") but have a couple of questions:

1. What use cases might justify bumping up the memory to 24Gb? I'm pretty sure for my current activity 16Gb would be fine but with the pace of AI, who knows?

Heavy photography work – especially with panoramas that involve stitching many photos together, and/or the use of many layers of stacking to get HDR (high dynamic range) effects. Heavy video editing. Running a guest OS like Windows 11 for ARM inside of a virtual machine. Possibly also software development.

2. I have a number of legacy USB A devices (scanner, hard drives, microphone) and am not sure whether to invest in a dock or a hub. To be honest I'm not sure of the relative merits of either. I would like to connect an ethernet cable and I may want to connect the laptop to a separate display at some point but otherwise my needs are reasonably straightforward.

There are various levels of hubs/docks including

• Simple USB-A hubs that plug into a USB-C port (directly or with the help of adapter), to give you four or more USB-A ports, but nothing else.
• USB-C hubs and docks with multiple types of ports. You can only connect one display to a plain USB-C dock.
• Thunderbolt hubs and docks with multiple types of ports. You can connect up to two displays (which do not need to understand Thunderbolt themselves) to a Thunderbolt dock, if the Mac in question supports them.

USB-A hubs and plain USB-C hubs/docks are a dime a dozen. If you are interested in Thunderbolt docks, I would suggest looking at the offerings from Other World Computing (MacSales), SonnetTech, and CalDigit – since those three companies have been in the business of supplying Thunderbolt gear to Mac users for many years.

3. I know the quality won't be as good, but would it be possibly to hook the MacBook Air up to the iMac, purely to use as a larger screen occasionally?

I don't know if your 24" 2017 iMac is the Retina model or the non-Retina model – but either way, it does not support Target Display Mode. That feature went away when the first 27" 5K Retina iMac came out in Late 2014 – and never came back.

Apple also added restrictions such that current Macs like the M4 MacBook Air do not support using ANY iMac as a Target Display.

See the bad news here: Use your iMac as a display with target display mode - Apple Support

Your iMac is also too old to act as an AirPlay Receiver for AirPlay to Mac, a lower-quality display method.

See the bad news here: Continuity features and requirements for Apple devices - Apple Support

johnzfoster wrote:

Hi,

I'm considering investing in a M4 MacBook Air (currently have Intel 2017 iMac 24") but have a couple of questions:

1. What use cases might justify bumping up the memory to 24Gb? I'm pretty sure for my current activity 16Gb would be fine but with the pace of AI, who knows?

The general rule is the more you have the better off you'll be... realistically, if you're not doing heavy video editing or something similar, 16GB is a good place to be. I'm a heavy user of office apps, remote server connections, etc. but I have no problems at all with the 8GB in my M3 iMac and my M4 MBA zips along noticeably faster with RAM usage never even budging out of the green in activity monitor unless I decide to crank up VMWare Fusion with a Windows 11 ARM VM running, and even then it only goes yellow and I don't notice any performance hit at all.

If you've been getting by with a 2017 iMac, you're going to be very happy whether you upgrade the RAM or not.

2. I have a number of legacy USB A devices (scanner, hard drives, microphone) and am not sure whether to invest in a dock or a hub. To be honest I'm not sure of the relative merits of either. I would like to connect an ethernet cable and I may want to connect the laptop to a separate display at some point but otherwise my needs are reasonably straightforward.

There's really no difference other than what they manufacturer decides to call it.

You don't really "dock" a Mac laptop. At least not like some of the old school Windows laptops that snapped into a big slab of a dock with a monitor and all kinds of ports connected to it. You're just going to plug something into the USB-C port. How it's physically laid out and what ports it has are a matter of preference and need.

3. I know the quality won't be as good, but would it be possibly to hook the MacBook Air up to the iMac, purely to use as a larger screen occasionally?

That's not going to work. That model iMac doesn't support target display mode and even if it did, the MBA doesn't support it.

Just buy an external monitor if you want one.

Would appreciate a steer, thanks

John Foster

You're very welcome!