x15, 3 monitors docking solution

@proting  If you want to run all of those displays from a dock, the only way to achieve it would be with a Thunderbolt dock that supports DisplayPort DSC, because Thunderbolt doesn’t have enough bandwidth to run that setup with uncompressed video, even before considering any non-video traffic you may want to run. The only dock I know of right now that could work would be the Lenovo Universal Thunderbolt 4 dock here. The top table for 2021 systems with DisplayPort DSC support here indicates that it can run quad 4K 60 Hz, which is roughly the same bandwidth as dual 4K 60 Hz + single 4K 144 Hz. Obviously Lenovo’s documentation won’t directly account for Dell systems, and I’m not even sure your system supports DisplayPort DSC, although I believe it does. Note also that you may need to use specific combinations of outputs on the dock to achieve your desired setup as noted in the table. But if that doesn’t work, then you may have to run 1-2 displays through some other output(s) on your system rather than trying to send everything through the dock.

A dock power output of 90W typically means that’s what it provides for the system AFTER reserving some capacity on its own larger power source to run itself and any accessories you connect. Current Dell docks that provide 90W are themselves powered by 130W adapters, for example.

90W would not be sufficient to run your system adequately, so you can and should keep your system’s own power adapter attached as well. You won’t damage anything.

Good luck, and if you try that dock, please report back about whether it worked for your rather high-end setup!

@proting  When you say “hub”, if you’re referring to a device that simply gives you more Thunderbolt ports, then as long as the hub actually supports video passthrough, you should be able to run your displays through a standard Thunderbolt 4 hub. But I’ve never tried that setup personally.

As for the article you found, the first half of your quoted sentence is correct, but the second half is poorly worded. It also fails to take into account that Thunderbolt’s 40 Gbps bandwidth includes both DisplayPort video traffic and PCI Express traffic. Thunderbolt 3 is required to have at least one DisplayPort video interface with two being optional and at least a PCIe x2 interface, with x4 being optional. With Thunderbolt 4, two DisplayPort interfaces and PCIe x4 both became mandatory. Dual 4K 60 Hz over Thunderbolt is achievable through a single port as long as the system has two DisplayPort interfaces wired to it (or a single DisplayPort interface if it’s specifically DisplayPort 1.4 AND that’s supported by the accessory you’re using), so yes you should still be able to run dual 4K 60 Hz displays from a single device. Even Thunderbolt 3 docking stations have been achieving that through a single connection to the system for a few years now.

I can’t speak to which of your two proposed solutions would be better since I haven’t personally used any of that equipment. The Lenovo solution seems easier since it would maintain a single cable connection to your system, but of course if it won’t work, then it’s not a better solution. Unfortunately I can’t speak from any practical experience here, only from my understanding of the underlying technology and what therefore SHOULD be possible.