PCIe 4 vs PCIe 3: Do you need Gen 4 in 2020?

DeckLink Quad 2 w Gen 4 PCIe x4 slot? pcie 4 slot But what about the fallback to PCIe , for example runs an older AMD or current Nvidia graphics card in such a slot? PCIe x4, PCIe x8, PCIe pcie4 slot SuperSpeed Storage：PCIe x4 Connector; EZ-Latch：PCIe x16 Slot with Quick Release Design; Fast Networks：GbE LAN; Extended Connectivity：DP, HDMI; Smart

pcie slot size Hi Community, any recommendations for Carrier Card with x16 Bandwidth having 4x Gen-4 slots and which fits low profile