Is a MacPro3,1 x16 slot PCIe or ?

PCIe x16: This is the largest PCIe slot with 16 data lanes PCIe x16 slots expansion card that connects to a computer's motherboard using a PCIe slot

PCIe compatibility and performance generates a LOT of confusion In Explaining PCIe Slots

pciex1_1 slot Concept Product CP074-1 4 x NVMe SSD to PCIe x16 Mobile Rack for PCIe Expansion Slot with Blower Fan and Aluminum Heatsink

pcie4 slot The term “PCIe card” and “expansion card” simply refers to hardware PCIe x1 • PCIe x4 • PCIe x8 • PCIe x16 These connections are