PCIe x4 vs x16 for single NVMe SSD speed increase?

My ten year old PC uses DDR3 memory and PCIe expansion slots, the x16 slot is occupied by the graphics card, no slot on the motherboard

SSDs come in various sizes and shapes, but the most common types of slots are M key and B+M key While both

m2_1 slot SATA SSDs and SSDs that use two PCI Express lanes tend to use keys B and M to maximize compatibility, since both connectors can deliver both

m2 slot types On the contrary, the L-series among others can only support cards using the PCIe standard in the WWAN slot Some notebooks (notably the Asus Eee PC, the