Removed my old HDD after transferring all data to the 2TB SATA SSD (which had its data transferred to the newly acquired 4TB M2 NVMe), detached one of the SATA power cables from the PSU and finished my cable management after relocating the SATA SSD from the HDD cage onto the backside of the mainboard.
The mainboard has dedicated M2 NVMe slots with a heatsink on it, both M2 SSDs got installed there.
SSDs with detached heatsink (gray cooling pads)