will a pcie 3.0 work in a pcie 4.0 slot
Can I Use a PCIe 3.0 Card in a 2.0 Slot? - PC Guide 101
A PCIe 4.0 NVMe SSD will work in a PCIe 3.0 M.2 motherboard slot at PCIe 3.0 speeds.
Question - PCIE 3.0 x8 into a PCIE 4.0 x4
That means a PCIe 4.0 Device in a PCIe 3.0 slot will work. However, it will be limited to operating at the max transfer rate of the PCIe 3.0 slot.
PCIe Slots & Lanes Explained: Choosing the Right Connection (Fast ...
However, PCIe devices are generally compatible with newer versions of the PCIe standard, so a PCIe 3.0 device can be used in a PCIe 4.0 slot, for example, albeit at a lower data transfer rate.
Can I Use a PCIe 4.0 Graphics Card in a PCIe 3.0 Slot? - TechReviewer
Yes, you can use a PCIe 4.0 card in a PCIe 3.0 slot. PCIe is designed to be backward compatible. However, the card will operate at PCIe 3.0 speeds, not taking full advantage of PCIe 4.0 capabilities.