content: You don't need PCIe 4. A single PCIe 3.0 lane, at 8GT/s, can send 985MB/s. Multiply that by 16 to see what you can really do - 15,760MB/s, or 15.39GB/s for PCIe 3.0 x16. The switch from SATA to PCIe is a big deal specifically because of how much more bandwidth is already available on that interface vs SATA III (which is only 600MB/s). For reference -  PCIe - http://www.tested.com/tech/457440-theoretical-vs-actual-bandwidth-pci-express-and-thunderbolt/ SATA III - https://en.wikipedia.org/wiki/Serial_ATA#SATA_revision_3.0_.286_Gbit.2Fs.2C_600_MB.2Fs.29