The HP EliteDesk 800 G5 Mini has no PCIe slots — RAM, SSDs, and Wi-Fi only

At roughly 177 × 175 × 34 mm, the G5 Mini is a flat little box with zero PCIe expansion. Any upgrades you want — RAM, M.2 SSD, 2.5-inch drive, wireless card — are confined to what’s already inside the chassis.