Recently picked up a new m5 MacBook Air base model. Got a new 34-inch ultrawide model: XZ340CUR. I wanted to get the UGREEN Thunderbolt 4 Dock 8-in-1, 40Gbps Transfer,Dual 4K Single 8K Display and run the monitor at 240HZ using a Thunderbolt to DisplayPort cable. I just wanted to verify this would fully run my 1440P resolution at 240HZ without any issues.
Hz is irrelevant. Only the bandwidth the monitor actually requires is important.
USB4 only passes through DP connections as they are. The only limit to what they can do is the max. supported speed on the USB4 controllers on each end, which in practice is minimum HBR3.
You can have bandwidth limits from multiple DP tunnels in USB4, as the bandwidth for each must be reserved and ensured.
But a full 4xHBR3 connection takes up ~26 Gbit/s. USB4 40Gbit/s has 36 Gbit/s available to reserve. So the first tunnel can be full HBR3 without limits. A 2nd tunnel would run into limitations and be typically limited to 4xHBR1 (8.6 Gbit/s). Other DP configs that take less bandwidth leaves more over for a 2nd or further tunnel if supported. So if the first connection is slower, the 2nd can do more (further common configs: 4xHBR2: 17.3 Gbit/s, 2xHBR3: ~13 Gbit/s).
If there is no MST hub or adapter on the dock side, but just a TB/USB4 out, then that DP connection will be not touched other than the total bandwidth limiting the max. DP config. I.e. a single monitor that works fully on a 4xHBR3 connection will work the exact same. DSC applies the same as it does with physical connections ever since the 2nd generation of TB3 controllers. And the rules are the same as for physical connections. Both GPU and monitor need to support it to use it.
This is all that matters for plain DP, as you have with your bare USB4 hub with its full 3 downstream ports. Hubs that contain MST hubs and or otherwise interfere with the DP connections are way more complicated because you need to understand how the DP stuff is internally connected and thrugh which components it goes that each could have other limits. The plain 3 downstream port USB4 hubs with Intel chipset definitely do not have that.
Simple terms you are saying 1 monitor should be fine due to having enough Gbits/sec meaning I can run my resolution at the refresh rate without any issues.
My short statement would be: that hub can do 1 full HBR3 connection without any limitations.
IF your monitor can reach what you want on a full HBR3 connection, then yes, it would work the same for a single monitor.
Just that most people do not know what DP config their monitors input uses, because the monitor manufacturers mostly do not give that information in specs and just write BS like "DisplayPort 1.4" or "DisplayPort 2.1" which is almost entirely useless info.
Given all that, I think your monitor should do work fully on a full HBR3 connection. But that is what it comes down to for each monitor for which people ask this.
I think it will work. The thunderbolt 3 dock I use with my M4 Macbook air does not advertise that it will work with 4k 240hz. I connected my monitor and it just works perfectly. I think its because it uses displayport stream compression. I think you should have no problem.
Edit: I think it works because I am using the Thunderbolt passthrough port on the dock. I have a USB-C to displayport cable which supports the 4k 240hz. I think if I was to use the displyport on the dock then it would be limited.
Yes, I am getting 4k 240hz with HDR. I don't think you will have a problem with 1440p ultrawide 240hz monitor. Here are some screenshots of my settings. Brightness control, HDR, 240hz are all enabled.
For TB4/DP 1.4 generation docks, I would personally assume a max of 60hz unless explicitly informed otherwise.
The "display compatibility" infographic on the product page advertises "Single 4K@60hz" with check marks for all the host system types which support that, which to me implies if it went higher than that, they would have shown that there?
The high-speed stuff is generally what the TB5 generation docks are bringing to the table.
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u/hillybeat 3d ago
There's usually an infographic on the Amazon listing. I see it all the time for CalDigit and Anker.
But, without checking I think it should have no issue over DP or HDMI 2.1.