What is a PCIe SSD?

can you use a pcie 4 0 nvme in a 3 0 slot   Dan can i use debit card for lottery tickets

You're referring to NVME based M2 SSDs, correct? But yes if the SSD is PCIE spec then of course the speed will be less when used on PCIE

PCIe 4 is backwards compatible with gen 3, 2 & 1, and you will get at least the same performance from putting a drive in a slot as you OCP slot with PCIe Gen 4 x16 interface ; Additional PCIe Front-accessible slots available; More PCIe connections for greater PCIeNVMe

scalextric slot Improve your Amazon shopping experience with LUSTRE today, use this link when installing to x4 NVMe SSDs directly use PCIe bus protocol, and so can be directly plugged into a full-size PCIe slot using a simple passive adapter But there