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

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Apr 12, 2001
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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.

Article Link: MacBook Pro With M4 Chip May Support Up to Two External Displays
 
Article Link
https://www.macrumors.com/2024/10/08/macbook-pro-m4-two-external-displays/
Last edited:
I use the main display and 2 other displays with my M1 MacBook Air all the time. Albeit not at that resolution
 
MacRumors said:
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).
Click to expand...

MacRumors said:
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.
Click to expand...

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. 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.
 
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galad said:
Every M3 Mac already supports two external displays (when the internal display is disabled).
So what's the news here?
Click to expand...
If it can support three displays in total then one would hope if you either rip off the built in display, or close it gently, then three external displays would work. Otherwise we're back to the 1970s style VDU again.
 
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"May".... the golden world to say nothing.

It´s not the number of ports. It´s the number of buses.
 
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MayaUser said:
here you dont have to disable anything
Click to expand...
IMG_0232.gif
 
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What is even more interesting is the chance that the M4 Pro/Max variants will support Thunderbolt 5.
The base M3 supports TB3, while the base M4 supports TB4. The M3 Pro/Max supports TB4, so there’s a chance the M4 Pro/Max will support TB5. Or the M4 Ultra the very least. Maybe with the announcement of a >5k 120Hz display from Apple that makes use of the doubled bandwidth of TB5…
 
I really can't imagine what using an M4 Max might be like. I just bought the M3 Max 16" MacBook Pro and the speed is insane. It is the closest think to real-time computing I have ever encountered outside of a lab setting with hardware costing 20 times the price of this. Amazing. I look forward to this new device appearing.
 
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Who gives. Bring that XDR 6k screenprice down to 1500/2000 max! Specially when no imac pro is coming.
 
springsup said:
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).
Click to expand...
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 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.
 
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MacRumors said:
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.
Click to expand...
AFAK there's a chicken-and-egg situation here. Remember: Thunderbolt 4 is USB4 with a bunch of features/minimum specs that are optional in USB4 made compulsory for Intel's Thunderbolt 4 certification scheme. One of those specs is that TB4 hosts must support 2 external displays via TB.

The ports on the current model are called "Thunderbolt 3 / USB4" because they only support a single external display, otherwise they'd already be TB4.

Evidence: if you compare the specs of the M2 MBA with the M2 Mac Mini, the former has "Thunderbolt 3/USB4" ports and the latter has "Thunderbolt 4" - same chipset with max. 2 displays, the difference being that Mini doesn't have a built-in display and can support 2 displays over TB.

galad said:
Every M3 Mac already supports two external displays (when the internal display is disabled).
Click to expand...

See above.
Either:
(a) the "internal display is disabled" caveat didn't meet the TB4 certification requirements, or
(b) The feature was enabled late in development (ISTR that some M3 Macs didn't have it at launch and got it via an aftermarket OS update) and wasn't available in time to get the ports certified as TB4.

TLDNR: Since the M4 has a new display controller (and everything we've seen so far is possibly knobbled by being in an iPad) it's quite plausible that the M4 will support more displays but TB3/USB4 vs. TB4 is pretty subtle, and might be a mistake by the leakers or might just be the current clamshell-mode support with Intel TB certification.
 
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