In article , Andrew Gabriel
writes

Particularly given the PCI bridge chip next to it, and that
PCI is an unterminated bus which relies on the signal reflection
from the far end of the bus in order to work. The bridge chip is
creating a new physical PCI bus, and it may be that the tracks to
the PCI devices on that bus are too short to meet any minimum
track lengths required for signal reflection detection, and need
to be artificially lengthed.

Tuned length termination stub sounds good to me.
--
fred
it's a ba-na-na . . . .