MetricTonto

In the end I went that route: ZFS Master set to manual refresh, and having Dynamix Auto Fan Control to exclude all the concerned drives from reading their temperatures, while setting the minimum PWM values to ones that can keep them decent while they are active (max rpm, these days 🫠). I need to do that because this old mainboard's BIOS is too limited and won't let me set a constant value: it varies it in real time based on a mix of CPU and chipset temperature reads.

So, it seems it's actually normal 🤔:
(Also, I'm realizing now that I didn't set the disconnected motherboard NIC to a different subnet before trying to make the Mellanox the primary one 😒. I'm not sure that would have solved the internet connection, but it certainly ought to have helped)
 
So, case closed, I think. Thank you all 🙂.