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:
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?