can use ddr3 in ddr4 slot | can use ddr3 in ddr4 slot

You can use a PCIe 4.0 SSD in a PCIe 5.0 slot, and it will work just fine, at PCIe 4.0 speeds. Similarly, a PCIe 5.0 SSD can be used in a PCIe 4.0 slot, but again, its performance will be limited to PCIe 4.0 levels.

The Dell OptiPlex 9020 SFF has 2GB DDR3 memory with four DIMM slots which can be upgraded to a maximum of 32GB DDR3. For storage, it has one 3.5-inch and two 2.5-inch SATA drive bays which can be upgraded with a Crucial compatible SATA SSD.

Are you looking for extra RAM memory to speed up your laptop? First, make sure to check whether it uses DDR3 or DDR4 RAM memory. Plus, always select a SODIMM. These modules are smaller because they are specifically developed for use in laptops.