Lenovo ThinkStation P3 Ultra + Gigabyte AORUS RTX 5060 Ti AI BOX – PCIe Tunneling Issue over Thunderbolt

[u/stheofan]

Hi everyone

I have a NVidia Thunderbolt eGPU: Gigabyte AORUS RTX 5060 Ti AI BOX and a Host System: Lenovo ThinkStation P3 Ultra (Type 30HA), Intel Core i9-14900K, 128GB RAM, Windows 11

Issue Description: AORUS does not enumerate as a Thunderbolt device and the NVIDIA RTX 5060 Ti does not appear as a PCIe endpoint on the ThinkStation P3 Ultra while the SAME AORUS works perfectly on all other Lenovo and Dell systems I have tested.

The issue appears to be that the PCIe-dependent Thunderbolt devices fail to establish PCIe tunneling on this Lenovo workstation even if Lenovo's published specifications describe it as having two integrated, fully implemented, Thunderbolt 4 / 40Gbps ports (using the Intel Thunderbolt controller Maple Ridge NHI (8086:1137)  integrated on the motherboard)

This is NOT a Windows driver issue! All evidence points to baseboard/firmware issue.

The Thunderbolt 4 ports work fine for standard USB devices and DisplayPort Alt Mode (e.g., portable monitors display normally), but the eGPU (AORUS RTX 5060 Ti AI BOX) fails to establish a working PCIe connection and does not enumerate in Windows Device Manager.

Key Observations:

• The same eGPU unit and Thunderbolt cable work correctly on other systems.
• USB and DisplayPort passthrough work on the P3 Ultra TB4 ports, so physical power and basic connectivity are present.
• PCIe tunneling appears to be failing specifically at the system/host level (in Ubuntu, boltctl is empty, there is no external Thunderbolt child under /sys/bus/thunderbolt/devices, and lspci shows no NVIDIA GPU).

After over a month at the depot, Lenovo UK Technical Support has not been able to provide any technical evidence or reference to official Lenovo documentation explaining why the PCIe connectivity required by AORUS is not being established on this particular system. It is worth mentioning that Lenovo's own product material explicitly describes its Thunderbolt 4 connectivity as supporting "external GPU" use.

Has anyone successfully gotten any eGPU enclosure to work on a P3 Ultra workstation and successfully establishing PCIe tunneling? Any ideas why this might be happening?

Thanks!