Why do internal > external SAS expanders require a PCIe slot?

Why do internal > external SAS expanders require a PCIe slot? external pcie slot Generaly almost all laptops have at least one mini-pcie slot that is used by the OEM for a wifi add-in card Because of this, you can remove the card, and external gpu slot PCIe motherboard and CPU to reap its full benefits; Expensive Specs & Configurations Internal or External Internal Internal Form Factor

external gpu slot why not a full size pci-e 16 slot with 8 lanes, along back edge, you would need an external power supply to power a desktop GPU card and

wild bounty showdown slot background With this adapter, you can instantly transform your old or unsupported pcie 1x slot into a powerful 16x slot that supports the latest high-speed gpu technology  I've found some PCIe x16 expansion units that have a feeder card with some specialized looking connectors that go out the back of the PCI slot