Thanks for answering. I did format my SSDs and reinstall the OS after I swapped the mobo.
My MoBo is v.1.1, according to the sticker on the box.
The problem with the hub (and the mouse) doesn't depend on the USB slot I pick, 2.0 or 3.0. It occurs around 60-70% time after the PC is restarted, for the mouse, and 100% time for the hub. It completly fixes itself after unplugging the device and plugging it back again. All my other USB devices, including another mouse I own, work perfectly fine. The issue occurs outside of OS as well, i.e. the mouse can go crazy in BIOS, too.
It's also worth to mention that the "bug" sometimes leaves the hub powered on (ie. it can charge my MP3 player) but it's not detected by Win10 nonetheless.
After the PC has worked some time, the chance of this strange bug occuring decreases upon system restart. Completely shutting down the system (turning the PDU off, for instance) pretty much "resets" the chance of this thing to occur.
Right now, I tried connecting the mouse to the frontal USB panel (which goes to the USB connector on the mobo, rather than going directly into the back ports), and on my 1 attempt it worked fine, both mouse and HUB. I'm pretty sure it's going to come back to haunt me anyway :<