240Hz Dual External Monitors on M4...

[rmbrown09]

Got my wife a base M4 14", connected to two displays. One via HDMI (running at 240hz) and one via HDMI into a dock that connects to the thunderbolt port, but will only allow 60hz.

I'm about to buy my own Macbook Pro and am deciding between the Pro and Max chip.
It seems the Pro should be able to handle dual 1440p 240hz displays... https://support.apple.com/en-us/101571

It's not working with my wife's system, but I think it's just because I'm not running a Thunderbolt 5 dock?
If I plug in two monitors via HDMI to a Thunderbolt 5 dock, I should be able to run them both at 240hz (1440p) on an M4 Pro... no need for the max right?

 

[rmbrown09]

Just tested and via HDMI, and the M4 MBP base supported 360hz on my 1440p monitor. Just need a DisplayPort to HDMI cable to arrive so I can test two monitors at once with this refresh rate.

 

[Alameda]

Just tested and via HDMI, and the M4 MBP base supported 360hz on my 1440p monitor. Just need a DisplayPort to HDMI cable to arrive so I can test two monitors at once with this refresh rate.

I don’t think you will find a DP to hdmi cable which will do that, but give it a shot.

 

[joevt]

Which dock, cable, adapter, display are you using?

HDMI 2.0 can do 1440p120 4:4:4 8bpc. Maybe 4:4:4 10bpc.
HDMI 2.0 can do 1440p240 4:2:0 8bpc.
DisplayPort 1.4 can do 1440p240 RGB 8bpc.
1440p360 requires DisplayPort 1.4 with DSC or DisplayPort 2.1 or HDMI 2.1.
Be sure to get a DisplayPort 2.1 to HDMI 2.1 adapter or cable.

All Thunderbolt and USB-C docks with an HDMI output are using a DisplayPort to HDMI adapter internally. In that case, it's better to get a dock with DisplayPort or USB-C outputs only, so that you can choose the DisplayPort to HDMI adapter and update just the adapter when a better one comes along. However, for DisplayPort 2.1, you'll need a minimum of a Thunderbolt 5 dock.

 

[Alameda]

Which dock, cable, adapter, display are you using?

HDMI 2.0 can do 1440p120 4:4:4 8bpc. Maybe 4:4:4 10bpc.
HDMI 2.0 can do 1440p240 4:2:0 8bpc.
DisplayPort 1.4 can do 1440p240 RGB 8bpc.
1440p360 requires DisplayPort 1.4 with DSC or DisplayPort 2.1 or HDMI 2.1.
Be sure to get a DisplayPort 2.1 to HDMI 2.1 adapter or cable.

All Thunderbolt and USB-C docks with an HDMI output are using a DisplayPort to HDMI adapter internally. In that case, it's better to get a dock with DisplayPort or USB-C outputs only, so that you can choose the DisplayPort to HDMI adapter and update just the adapter when a better one comes along. However, for DisplayPort 2.1, you'll need a minimum of a Thunderbolt 5 dock.

I don’t think there is such a thing as a DisplayPort to HDMI 2.1 cable. DisplayPort to HDMI was called DP++, and it was limited to 4K30. So it was great for 1080p, but technology has evolved from there.

 

[rmbrown09]

I ordered this cable: https://a.co/d/3EqM0vn
My displays support dual HDMI out and display port out. My gaming PC is plugged into the display port slots so trying HDMI here.

 

[Alameda]

I ordered this cable: https://a.co/d/3EqM0vn
My displays support dual HDMI out and display port out. My gaming PC is plugged into the display port slots so trying HDMI here.

It sounds like it’s an active cable which converts DisplayPort into hdmi 2.1. Impressive.

 

[PaulD-UK]

@rmbrown09 “I ordered this cable…”
Cable Matters: “Max Resolution on macOS is 4K 60Hz”

Is Amazon showing different cables in different geographical sites?

 

[rmbrown09]

@rmbrown09 “I ordered this cable…”
Cable Matters: “Max Resolution on macOS is 4K 60Hz”

Is Amazon showing different cables in different geographical sites?

No I just can’t read.

Thunderbolt 5 dock? Not sure what I need exactly or if I need the Max chip.

 

[Alameda]

@rmbrown09 “I ordered this cable…”
Cable Matters: “Max Resolution on macOS is 4K 60Hz”

Is Amazon showing different cables in different geographical sites?

Yes, but several reviewers reported that they get 4K240 with MacOS. One even included a screenshot.

It’s all explained in this thread:

https://forums.macrumors.com/threads/dp-usb-c-thunderbolt-to-hdmi-2-1-4k-120hz-rgb4-4-4-10b-hdr-with-apple-silicon-m1-m4-now-possible.2381664/

 

[joevt]

I don’t think there is such a thing as a DisplayPort to HDMI 2.1 cable.

There exist DisplayPort to HDMI 2.1 adapters/cables. Most are DisplayPort 1.4 to HDMI 2.1 but there may exist DisplayPort 2.0 to HDMI 2.1 adapters as well.
https://www.paradetech.com/products/ps196/
https://us.caldigit.com/products/dp20-hdmi21
https://insights.club-3d.com/thread/cac-1087-with-nvidia-rtx-2070-super-and-lg-oled-c2/

https://www.reddit.com/r/CalDigit/comments/12gr85m/displayport_20_to_hdmi_21_adapter

DisplayPort to HDMI was called DP++, and it was limited to 4K30. So it was great for 1080p, but technology has evolved from there.

DP++ (a.k.a. DisplayPort Dual Mode) is a feature of some DisplayPort ports to directly connect HDMI devices using a passive adapter. The passive adapter just needs to change voltage levels. Some were capable of 4K60 but usually they were limited to 4K30.

Active DisplayPort to HDMI adapters are required for DisplayPort ports that don't support DP++ or for higher bandwidth.

USB-C supports DisplayPort but not DP++. There does exist a USB-C HDMI Alt Mode but I don't think anything uses it. Therefore, all USB-C to HDMI adapters are active adapters.

I ordered this cable: https://a.co/d/3EqM0vn
My displays support dual HDMI out and display port out. My gaming PC is plugged into the display port slots so trying HDMI here.

You mean your displays support both HDMI and DisplayPort input. Displays don't usually have any outputs (except some have a DisplayPort out for chaining multiple displays using MST).

@rmbrown09 “I ordered this cable…”
Cable Matters: “Max Resolution on macOS is 4K 60Hz”

Is Amazon showing different cables in different geographical sites?

They show this:

Does this Cable Matters USB-C to HDMI 2.1 cable support 4K@120hz on macOS?

Yes, Cable Matters has developed custom firmware for this product to enable 4K@120Hz RGB 10-bit HDR support on macOS. For more information, please search "Cable Matters Firmware Update Tool [4K@120Hz on macOS]" on Google.