PCIe VS : What are the differences and similarities?

By specification, all PCIe cards are backwards compatible with the lowest bandwidth x1 lane slots If the x1 slot is designed with an open end,

PCI Slot x 3 30423052 B-Key x 1 Mini PCIe Slot x 1 Micro SIM Card Slot x 1

pcie slot pinout So, while even a single x1 PCI Express slot is far more capable than a set of PCI slots, USB or Firewire ports, it doesn't necessarily mean that

pcie 40 gpu in 30 slot SATA card for PCIe x1 slot with 8 ports Bizarro