MacBook Pro With M4 Chip May Support Up to Two External Displays

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Apple's upcoming entry-level M4 14-inch MacBook Pro may be capable of supporting up to two external displays with the lid open, up from one display supported in the current M3 model, if recent leaks are anything to go by.

YouTube Short by romancev768 allegedly confirming the dual display support

Apple's existing M3 14-inch MacBook Pro comes with two Thunderbolt 3 USB-C ports, not three Thunderbolt 4 ports like the 14-inch and 16-inch MacBook Pro models powered by M3 Pro and M3 Max chips.

Apart from fewer USB-C ports, the lack of Thunderbolt 4 support on the 14-inch MacBook Pro with the base M3 chip means it only supports one display with up to 6K resolution at 60Hz (or one display with up to 4K resolution at 120Hz over HDMI) when the lid is open. Currently the only way to support to two external displays simultaneously is with the lid closed, based on the resolution (up to 6K) and refresh rate (up to 60Hz) of each external display.

However, assuming the alleged Russian leaks of Apple's unannounced 14-inch MacBook Pro with an M4 chip are reliable, the new M4 variant of Apple's entry-level 14-inch MacBook Pro will come with three Thunderbolt 4 ports, as opposed to the two Thunderbolt 3 / USB4 ports found on the current model. This would mean it can support two external displays with the lid open instead of just one.

While the upgrade from two TB3 ports to three TB4 ports has yet to be confirmed, such a change would better align the entry-level machine's capabilities with Apple's more powerful MacBook Pro models.

Here's a reminder of the different display configurations possible on the M3 Pro and M3 Max models:

M3 Pro MacBook Pro:

Supports up to two external displays:

  • Two 6K displays at 60Hz over Thunderbolt, or
  • One 6K display at 60Hz over Thunderbolt and one 4K display at 144Hz over HDMI

M3 Max MacBook Pro:

Supports up to four external displays:

  • Three 6K displays at 60Hz over Thunderbolt and one 4K display at 144Hz over HDMI, or
  • Two 6K displays at 60Hz over Thunderbolt and one 8K display at 60Hz over HDMI, or
  • Two 6K displays at 60Hz over Thunderbolt and one 4K display at 240Hz over HDMI

Additional features for both M3 Pro and M3 Max:

  • Native DisplayPort over USB-C support
  • HDMI port supports either:
    • One 8K display at 60Hz, or
    • One 4K display at 240Hz

We should know for certain what the specs are for the base M4 14-inch MacBook Pro before the month is out. Apple is expected to announce new iMac, Mac mini, and MacBook Pro models with M4 chips towards the end of October, with at least some of the new Macs rumored to be released on November 1.

Related Roundup: MacBook Pro
Tag: Thunderbolt 4
Buyer's Guide: MacBook Pro (Neutral)
Related Forum: MacBook Pro

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Top Rated Comments

JackLeBoul Avatar
JackLeBoul
7 months ago
Yeah, it's not confusing at all.

After rereading it all, I would need a numbers spreadsheet to figure out which chip can power how many screens at what resolution at what Hz.
Score: 14 Votes (Like | Disagree)
Chancha Avatar
Chancha
7 months ago

Does using 2 displays require so much power? Or is it just a fake limitation?
It requires actual space on the chip for dedicated display engines, which was at a premium for M1/2/3. Apple took feedback and is willing to add more of them, but as usual with chip design, it took years to realize.
Score: 11 Votes (Like | Disagree)
F23 Avatar
F23
7 months ago
we are in the golden era of MacBooks
Score: 8 Votes (Like | Disagree)
AdmiralKirk Avatar
AdmiralKirk
7 months ago
Finally. My wife’s Intel MacBook Air from early 2020 can support 2 external 4k monitors and its own.

Its not really acceptable that it has taken until q4 2024 for Arm based Mac’s to catch up ?
Score: 8 Votes (Like | Disagree)
springsup Avatar
springsup
7 months ago

Apart from fewer USB-C ports, the lack of Thunderbolt 4 support on the 14-inch MacBook Pro with the base M3 chip means it only supports one display with up to 6K resolution at 60Hz (or one display with up to 4K resolution at 120Hz over HDMI).

The M3 Pro-powered MacBook Pro models also support one external display with up to 6K resolution at 60Hz over Thunderbolt and one external display with up to 4K resolution at 144Hz over HDMI.
There is an important, subtle detail here: Apple seems to have intentionally degraded HDMI over USB-C, so it can’t do uncompressed 4K 120Hz 10-bit. That is only available via the built-in HDMI port, or DisplayPort over USB-C (albeit with compression that wouldn’t be needed over HDMI).

Users on these forums have discovered hacks to work around it ('https://forums.macrumors.com/threads/dp-usb-c-thunderbolt-3-4-to-hdmi-2-1-4k-120hz-rgb4-4-4-10b-hdr-with-apple-silicon-m1-m2-m3-now-possible.2381664/'). It involves buying a specific USB-HDMI adapter and flashing a custom firmware to trick the computer in to thinking it’s a DisplayPort adapter. So clearly there is no hardware limitation - it’s possible to do it, but you need to work around the fact that even as an Apple customer, Apple hates you for using a third-party monitor and will vindictively degrade your experience, and that external display support on macOS is utter trash in general. Go shopping for any USB/Thunderbolt dock and the product page will be full of caveats warning Mac users that they will have a far inferior experience than Windows users.

This should be a disclaimer on any post relating to MacBooks, especially those relating to external displays.
Score: 8 Votes (Like | Disagree)
theluggage Avatar
theluggage
7 months ago

Apple seems to have intentionally degraded HDMI over USB-C, so it can’t do uncompressed 4K 120Hz 10-bit. That is only available via the built-in HDMI port, or DisplayPort over USB-C (albeit with compression that wouldn’t be needed over HDMI).
If DisplayPort needs compression for "4K 120Hz 10-bit" then no USB-C-to-HDMI device can officially do uncompressed 4K 120Hz 10-bit since HDMI Alt Mode is dead ('https://arstechnica.com/gadgets/2023/01/hdmi-to-usb-c-spec-axed-as-displayport-alt-mode-reigns-supreme/') and virtually everything has to go via DisplayPort alt mode or DisplayPort-over-Thunderbolt to a DP-to-HDMI converter instead - in which case any "4K 120Hz 10-bit" content has been compressed using "visually lossless" (i.e. not lossless, then) compression and anything "lost" in that process will stay lost after it is de-compressed: calling the result "uncompressed" is, well, like selling "fresh fish" when it has been previously frozen...

Not necessarily defending Apple here, but it sounds more like "nannying" by not supporting an unofficial kludge rather than an evil plan.
Score: 6 Votes (Like | Disagree)
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