What is the correct way to insert hot-swap SAS into Supermicro?

Question

Iron

I'll start from afar. Once upon a time, about 6 years ago, a server was bought and assembled by specialists from a computer store. Since then, the person under whose leadership the server was going has died. The professionals have retired.
Hardware - SuperChassis 745TQ-800, it has Supermicro X8DTN +, RAID 1E of 4 SAS drives in a basket, another SAS in a basket + 2 SATA SSDs inside the case.
LSI SAS1064E RAID controller (plugged into PCI), 4 SAS disks are plugged into it.
Problem - I need to insert another hot-swap SAS disk for backup.
What happens when a disk is inserted into the next free slot after the RAID array - the server freezes at the start.
What happened when the disk was inserted into the other two free slots - the server starts to boot with Windows 2003(!) and then reboots.
I climbed into the BIOS, found the RAID set there, switched to AHCI. The server booted into a normal system, at the same time the RAID problem signaling on the basket turned off. There is no disk in the bios.
I got into the raid utility, it also does not see the disk. On mat. The board is all right and the connectors from the basket are connected.
Tell me where to dig? The disc is brand new and has never been used before.

Answer 1

On mat. The board is all right and the connectors from the basket are connected.

Check if all buckets are connected to the RAID controller? Or to the mother?