Hp z840 Thunderbolt card Internal Connectors

[DGroves]

reading the HP service manual for the z820 i see P25-P25 are USB 2.0 headers

with 3 wires going to p-25 and 2 wires to p-26

i suspect that the 3 wire cable has either ground and/or power as one of the connections this can be traced/checked using a multimeter and probing the card header pin(s) of each to the pci-e  connectors power/ground pins

and p-25 p26- each have a platform sequence control connection (just a guess)

[TyeB]

I like your logic, makes sense to me. I'll give it a crack and let you know how it works out. Thanks for your help with this, really appreciate it.

[DGroves]

look at this pdf showing the connectors c25/c26 going to the thunderbolt card for the z820/z840

both  c25/c26 connectors appear to be two rows of 4 pins on each connector

and the picture somewhat shows which pins in each socket is in use , then shows the cable going to the TBolt card header

hope this helps you

https://www.manualshelf.com/manual/hp/hp-thunderbolt-2-pcie-1-port-i-o-card/thunderbolt-add-in-card-...

[DGroves]

another kind user who has the z820/z840 gpio cable took pictures of it which may help further

https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/HP-z820-Thunderbol...