Can I Use a PCIe 4.0 Graphics Card in a PCIe 3.0 Slot? - TechReviewer
Yes, you can use a PCIe 4.0 card in a PCIe 3.0 slot. PCIe is designed to be backward compatible. However, the card will operate at PCIe 3.0 speeds, not taking full advantage of PCIe 4.0 capabilities.
PCIe 3.0 vs 4.0: What’s the Difference and Which Is Better - MiniTool ...
So, you can insert PCIe 4.0 expansion cards into PCIe 3.0 slots, but your data transfer rate will be limited by the slower speeds of PCIe 3.0.
PCIE Gen 4 confusion | TechPowerUp Forums
Similarly, if a PCIe 4.0 device is installed in a PCIe 3.0 slot, it will still run at PCIe 3.0 speeds. The compatibility only ensures that users can upgrade or build systems with mixed-generation components without facing compatibility issues.