Typically you get to safely use 2-3 NVME / PCIE drives and then anything else will disable a pair of SATA ports w/ a SATA M2 inserted into the remaining socket. There aren't enough PCIE lanes off the CPU or DMI to support more drives with adequate bandwidth.
▪ M2_3 slot (From
Z690 chipset)
▫ Supports PCIe 3.0x4
▫
Supports SATA 6Gb/s
▫ Supports 2242/ 2260/ 2280 storage devices
▪ M2_4 slot (From
Z690 chipset)
▫ Supports PCIe 4.0x4
▫
Supports SATA 6Gb/s
▫ Supports 2242/ 2260/ 2280 storage devices
So, both of those are being pushed through the DMI which has roughly 16GB/s of speed available which is why you have Gen 3&4 depending on the slot as Gen3 tops out at 3.5GB and Gen4 7GB/s which would still leave you with ~5GB/s for other devices like SATA spinners @ 300MB/s / 1.8GB/s for 6 of them. or if you go SSD you're pushing the limits at 500MB/s per drive / 3GB/s
Then you have all your other misc. functions tied to DMI.
View attachment 72306