can i use pcie 4.0 in 3.0 slot

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.

Likewise, a PCIe 3.0 SSD also can be inserted into a motherboard with PCIe 4.0 slot, and you will only get PCIe 3.0 performance.

Intel® 11th & 10th Gen Processors. 1 x PCIe 4.0/3.0 x16 slot*. - Intel® 11th processors support PCIe 4.0 x16. - Intel® 10th processors support PCIe 3.0 x16.