HP EliteDesk 800 G6 Mini — no PCIe slots, M.2 and 2.5-inch storage only

The EliteDesk 800 G6 Mini has no PCIe expansion slots at all. Storage is limited to the single M.2 NVMe slot and the 2.5-inch bay, though the flex I/O port on the rear can add a second DisplayPort, VGA, or serial port — useful for display expansion, but not for internal hardware upgrades.