General question

[Greedyboat8]

Would any laptop with a thunderbolt 3 port be able to use a 1080p 144hz external monitor assuming the gpu can handle it or do you have to use displayport/mini-displayport

because looking around for information people say that the thunderbolt 3 ports are connected to the Intel iGPU and not the dedicated one so i just want to confirm this information and if it was right.

[SkyHound0202]

Thunderbolt 3 has an DisplayPort alternative mode that can allows transfer of streams of DP signal between iGPU and an external display adapter (either relative input source like eGPU, or output like screen) over Thunderbolt connection.

It's bi-directional, hence the bi-directional arrow in the diagram.

In "Output" mode, the Thunderbolt 3 cable serves as a display cable to transfer the iGPU display data to an external display, while also carrying other protocols.

In "Loopback" mode, the display data is carried from eGPU through the Thunderbolt cable back to the iGPU, then displays on the laptop screen.

The problem is that the bandwidth of the Thunderbolt cable is limited. "Loopback" mode will devote additional bandwidth for the return signal from the eGPU in addition to PCIe and USB protocols, which would cause a contention of physical bandwidth, thus the performance drops when using the laptop screen as the primary display with eGPU on Thunderbolt.

So, as long as the CPU is powerful enough, and the Thunderbolt 3 is at its max speed (affected by controller, PCIe lanes and cable quality), a laptop should be able to drive a 1080p 144hz  monitor that is connected to eGPU with no problem.