Thank you Casey for your answer!
I just installed Mojave instead of Catalina, I thought I would run into less troubles. Now that I have Mojave running and It wasn't that hard, I may upgrade to Catalina soon. You're right, the PCI menu shows 2 thunderbold cards :thumbup:
Updated from 10.8.4 to 10.8.5 through app store, installed audio drivers (ALC8892 no DSDT) via Multibeast, and everything is working ok, including overclock (i52500K @4500).
Thanks Tonymac for everything!