RTX 3060 Laptop GPU - DisplayPort MST - Daisy-Chain vs Hub?

[sibobby1]

Does the RTX 3060 Laptop GPU Support both MST via Daisy-Chain and MST Hub?

I’m now trying to find a way to power my 3x HP EliteDisplay E240q’s with the least amount of physical connections as possible.

I tried researching on this forum, and I’m discovering mixed feedback about MST support:

GeForce RTX3060 MST (DaisyChain)

Hey Nvidia-People, I just got updated that the GeForece RTX 3060 says that it uses DP1.4 ports, but doesn’t support MST. I didn’t find any online source that stated that this wouldn’t be useable. I thought that MST was first possible at DP1.2 and must be integrated since DP1.3, so why can’t i use it with my RTX3060? Is there a Software or Firmware Update available for that? BR Andreas Dellmour

Nvidia agent MarkusHoHo explained that Nvidia doesn’t support MST Hubs. User c.cura confirmed that they had success driving 3x Dell U2723QE Monitors via DisplayPort Daisy-Chain.

My 2560x1440p 60 Hz displays would need ~ 6.64 Gbps of bandwidth each. ~ 19.92 Gbps for all three displays. Mini DisplayPort 1.4 is capable of 32.4 Gbps Max Specification Bandwidth and 25.92 Gbps Max Effective Bandwidth. The Intel Guide recommends if using MST, the sum of your signals should be less than the Max. Effective Bandwidth of the cable. 19.92 Gbps < 25.92 Gbps. This math checks out.

After reading the TrippLite / Eaton reference guide, they explained that MST can be configured using either Daisy-Chained Monitors or MST Hubs.

The VESA Presentation on DisplayPort Technical Overview explains how MST works with passing along the links to sequential Branch Devices. It sounds like behavior is equivalent using Daisy-Chain or MST Hub.

I contacted the MST Hub manufacturer. They sent me a replacement unit incase the first one was DoA. I contacted MSI and they told me the mDP 1.4 port is directly connected to the Nvidia GPU. This is completely up to Nvidia. I contacted Nvidia, and they told me to reach out on this Developer / GPU Hardware Forum.

I know the referenced Nvidia forum post says that Nvidia doesn’t support MST Hubs, but I don’t understand why. I understand it is not preferable from a performance standpoint - ideally they would like you to connect 3 separate displays to 3 separate ports, providing 100+ Gbps of bandwidth to an application which only needs <20 Gbps… I’d rather the convenience of less I/O for easy portability purposes. I’d also not rather shell out $1800+ in monitors that support MST Daisy Chaining, like the ones referenced in the above thread.

I don’t understand, from a technical standpoint, how MST can be supported in a daisy-chain configuration, and not via an MST hub. From the GPU’s perspective, shouldn’t it be equivalent? To my understanding, there is no special magic happening in a monitor that has MST Daisy-Chaining. An MST Hub replicates that same built-in behavior, just externally from the display, in its own enclosure.

Is there something I’m missing here?

Thanks
-Sibobby1

[MarkusHoHo]

Hi there sibobby1,

Are you referring to this KB article we have on the topic of MST Hubs?

That might be a bit misleading since it specifically mentions Tiled Displays for Info walls or similar, which would be usable with NVIDIA MOSAIC.

For normal “simple display” operation in Windows we should in fact support MST Hubs as well. Did you try a specific device which does not work? It is nearly impossible for our QA to test compliance with every single device on the market.

Thanks!

[sibobby1]

Hi Markus,

Thanks so much for the quick reply.

I was referring to this comment:

GeForce RTX3060 MST (DaisyChain)

Hi again, sorry this took a bit longer. I received confirmation now from engineering that the 3060 by supporting DP1.4 will also support MST and DisplayPort daisy-chaining. We do NOT however support MST Hubs, that is why I asked about those. This information was lost in communication between NVIDIA and the Help-desk personnel you received your original reply from, this sadly happens on rare occasions. I hope I could help!

Particularly:

“I received confirmation now from engineering that the 3060 by supporting DP1.4 will also support MST and DisplayPort daisy-chaining.
We do NOT however support MST Hubs, that is why I asked about those.”

Before I knew this, I tried using an MST Hub unsuccessfully. I tried troubleshooting by researching online and came across this older thread linked above. I saw that MST Hubs weren’t supported, but couldn’t understand why they wouldn’t be.

After your most recent confirmation that MST Hubs should be supported, I tried ordering a few more hubs, and I can report that it is indeed working. My sincerest apologies.

For anybody else that stumbles across this thread I’m using the following MST Hub from Amazon:
“HEZOOMS 8k DisplayPort Splitter 1 in 3 Out 8K@30Hz 4K@120Hz DP 1.4 Splitter Triple MST SST Hub Adapter 1x3 Port for 1 DisplayPort Ultra HD Source to 3 HD Display Port”

On the display input, I’m using a mDP → DP Cable from my laptop to the hub.
On the power input, I’m measuring 5V 0.41A (~2W) over the USB Micro B input
On the display outputs, I’m using 3x 2560x1440 60 Hz HP E240q’s using DP → DP cables.

Thanks so much for the support.
-Sibobby1

[MarkusHoHo]

That is great to hear, thank you for the update!