Thanks for the response.

I think it was just a coincidence that the eGPU started working with acpi=
=3Doff.=20
Taking a closer look at the issue it really does appear to be a BIOS problem
that prevents the proper PCI resource allocation to one of the TB PCI bridg=
es.=20
In fact when I took a closer look at the dmesg with acpi=3Doff I still see =
the
resource issues present.

I've opened up an official bug report here with the kernel ACPI BIOS team h=
ere:
https://bu=
gzilla.kernel.org/show_bug.cgi?id=3D201527

I realize the issue should really be solved by the manufacturer, but perhaps
the kernel devs can create a work around and/or have more direct lines of
communication with the Dell engineers.  Thank you both for your suggestions=
 and
comments.

Rob