What is the difference between PCIe Gen 3 and PCIe Gen 4?

What is the difference between PCIe Gen 3 and PCIe Gen 4? pcie gen 4 in gen 3 slot PCIe has retro-compatibility, that's for the X16 slot you use for the GPU and the M possibly SATA controlled pciex1 slot The good news is that all PCIe components are compatible with PCIe slots; this includes motherboards, graphics cards, SSDs, and other components that

pcie m2 slot 2 x16 Gen 4 Card uses PCIe , which doubles the bandwidth per lane compared to PCIe With four slots, it offers up to 256 Gbps of bandwidth per card,