• Guest, The rules for the P & N subforum have been updated to prohibit "ad hominem" or personal attacks against other posters. See the full details in the post "Politics and News Rules & Guidelines."

A dual-port Thunderbolt 3 controller in laptop has 22gbps or 32gbps aggregate PCIe data bandwidth?


Junior Member
Jan 28, 2018
Hi forum,

A painful aspect of the Thunderbolt 3 ecosystem is that Intel not even has clarified how much PCIe data their dual-port Thunderbolt 3 controllers used in laptops, actually have.

Each Thunderbolt 3 port does 22gbps full-duplex PCIe data, so 22gbps up and 22gbps down. (The "40gbps" figure is only marketing, and counts displayport and USB and what not.)

The Thunderbolt 3 controller is x4 PCIe lanes so has theoretical 32gbps full-duplex bandwidth to the CPU.

Say CPU is trying to feed each TB3 port with 16gbps of PCIe data, and that the TB3 device on each of the two TB3 ports is trying to feed the CPU with 16gbps of PCIe data - should this data go through, or will the controller cap it?


You need to have the answer to this question, to be able to decide whether using the second TB3 port at all is meaningful, or if you can as well just daisy-chain. This in turn is decisive for choosing what eGPU enclosure to buy, e.g. Akitio Node Pro versus Razer Core X.

Please let me know your thoughts, thanks!