I found this
PCIe Slot PCIe address Note GPU Number
1_1 09:00.0 white GPU0
1 02:00.0 black GPU1
2_1 0C:00.0. white GPU2
2 01:00.0 black, 16x GPU8
3_1 0D:00.0 white GPU3
3 03:00.0 black GPU4
4_1 0E:00.0 white GPU7
4 04:00.0 black GPU6
5_1. 0F:00.0 white GPU5
5 05:00.0 black GPU9
6_1 0A:00.0 white GPU10
6 06:00.0 black GPU11
7_1 0B:00.0 white GPU12
At:
https://www.reddit.com/r/MoneroMining/comments/7eq9vv/postit_pcie_logical_and_physical_slot_numbering/But no confirmation that's the numbering for Linux. I've used a few of these motherboards, was able to trial & error to replace risers to get them stable but on my new one if I could know for certain what port GPU7, 8 & 9 are it would make troubleshooting WAY easier!