Out of the box, any M.2 NVMe SSDs connected to the Dell OptiPlex 3060 runs at PCIe Gen 2.0 speeds (Max 5 GT/s; 2 GB/s) so the speed tests look like this:

However, after this BIOS mod, the SSD can reach PCIe Gen 3.0 speeds (Max 8 GT/s; 3.9 GB/s) so the speed tests look like this: