How many maximum SATA lanes does a motherboard support via PCIe-x1 adapters?

Question

motherboards

The essence of the question is purely sports (and a little bit practical).
What exactly should I look at to understand how many maximum SATA hard drives I can connect to the motherboard?

At the moment, the maximum that has turned out is 6 disks in the motherboard + 6 in the PCIe-SATA adapter. Although the adapter is 8 ports. And if you leave 4 disks in the motherboard, then the adapter gives 8. In total, it does not see more than 12.
If you connect a USB flash drive - then 11 + flash drive.

Ie this is some kind of limitation in the BIOS or chipset. But I can't find where to look anywhere. And even then, 12 ports is the maximum of all motherboards that I have on hand.

Judging by the reviews of these same motherboards, the number of SATA depends on the soldered controllers on the motherboard and the number of PCI-e lines in the chipset.
But somehow it is not clear why, if the adapter uses only one PCI-E line, the system does not see more than 12?

And if you stick 4-5 risers with video cards into the room, for example, they see each other normally.
Where is the disk limit?
Can this be seen in the datasheet?

Are there any experts in this area?

Answer 1

Yes, you can connect as much as you like. There are PCIE hubs, there are SAS controllers for dozens of disks. A limitation in the BIOS is possible, this is up to the manufacturer of the motherboard to you. But you need to look at them in the BIOS? In the system, everyone will see.

Answer 2

yes, in general, we have servers with 40 disks on sata adapters, then write it