High Refresh Rate Monitor locked at 60hz

[Gabe-N-Olivas]

Im having an issue in macOS where my monitor doesn't have a High Refresh Rate option when connected.

Here's what I'm working with:

1. I have two monitors a 27inch 1440p display which supports 165hz over DisplayPort (we'll call this display 1) and another which is a Wacom One Drawing tablet at 1080p60hz (we'll call this display 2)

2. This is a MacBook Pro M1 Pro running the latest version of macOS (15.0.1) so it supports multiple displays

3. These monitors are hooked up to a dock. Display 1 is hooked up to the downstream thunderbolt port on the dock through a thunderbolt to DisplayPort cable. Display 2 is connected to the dock's HDMI port

Here's what I know:

1. It's not a bandwidth issue. When I plug in monitor 1 on it's own it shows up as 1440p at 144hz and when I plug in display 2 it remains this way after. It's only when I plug my MacBook into my dock with both monitors attached that I see this behavior

2. t's probably not a dock issue. Ive tried both connecting the cables directly to my MacBook. In every configuration (HDMI in dock DisplayPort to MacBook, DisplayPort in dock HDMI in MacBook, etc.)

3. it may be a timing issue. I read that when a display connects first it takes priority in macOS but I'm not sure how (something about HBR3 and HBR2)

Any help would be appreciated. Thank you!

[waydabber]

Not sure about the dock and what connection it uses. If it is a Thunderbolt dock and connects both displays as multiplexed (daisy-chained) displayport stream to the thunderbolt connection then I think higher than 60Hz refresh rate should be available. If it's some kind of DisplayLink dock then it won't work.

[Gabe-N-Olivas]

It's a thunderbolt 3 dock, a Kensington SD5560T specifically https://www.kensington.com/p/products/device-docking-connectivity-products/laptop-docks-usb-accessories/sd5560t-thunderbolt-3-and-usb-c-dual-4k-hybrid-docking-station-96w-pd-windowsmacos/

[scottw1204]

MacOS and the M Series Macs are a bit fussy with monitors and refresh rates over 60hz especially when connected via a dock. The issue relates to limitations of Thunderbolt and the type of HDMI or DisplayPort standard in your dock.

Just so I'm understanding correctly, everything is running through a single Thunderbolt 3 dock connected via 1 Thunderbolt 3 cable, yes?

I have an M3 MacBook Pro and had similar problems. In my case, I was trying to run three 4K displays at 120hz HDR. I had to connect two displays to two different Thunderbolt ports and connect the third through a Thunderbolt 4 dock that was on its own Thunderbolt port. Each connection also used a special Cable Matters 48 Gbps USB-C to HDMI 2.1 Adapter with firmware specific for macOS (this is important as most adapters are not fully compatible with high refresh rates on Macs).

I tried connecting two displays to the dock, but they immediately kicked down to 60hz. I spoke with the dock manufacturer, and they said it's due to a bandwidth limitation of Thunderbolt 4. You have Thunderbolt 3 (even less bandwidth), so I'm guessing your dock might be slowing the refresh rate to standard 60hz once the second display is attached.

If your goal is a single connection for everything, you could try a different approach. They make a “USB-C Extender for MacBook with Case" made by Afterplug (on Amazon), which is essentially two Thunderbolt ports glued together into one plug. You could connect one display to the first port on the extender and your dock+display to the second port. iVanky makes the FusionDock Max 1 that supports multiple displays at high refresh rates, but to make it work, they use the same double-thunderbolt connection idea.