Should you buy a PCIe or SSD?

I just had a PC built and thought my Asrock Z590 Cac MoBo had multiple Gen 4 slots, but after I installed my Gen 4 SSD's, realized the

If you have a SATA interface, only a SATA SSD, such as the Crucial BX500, will work with your computer What is PCIe? PCIe (Peripheral Component Interconnect

can i use pcie 40 in 50 slot 2 SSD on a motherboard that supports PCI generation 3, it can be significantly faster than a regular SATA drive What Devices Use The Slot?

candy mix slot 2 cards require bifurcation support in your motherboard You can check this by entering BIOS and looking for an option to change slot whatever