How will a PCIe Gen x 4 SSD perform in a PCIe slot?

pcie 3 0 x4 slot   Dan pcie 40 gpu in 30 slot

I run a PCIe Gen 3 x4 NVMe SSD through my chipset coming from a Gen 2 x4 slot And at around 1700 MBs reads it just stops But it really

SuperSpeed Storage：PCIe x4 Connector; EZ-Latch：PCIe x16 Slot with Quick Release Design; Fast Networks：GbE LAN; Extended Connectivity：DP, HDMI; Smart 2 slots — supporting both PCIe and — that allow you to expand your system with high-performance SSD storage Designed for the latest generation of NVMe

great slot SuperSpeed Storage：PCIe x4 Connector; EZ-Latch：PCIe x16 Slot with Quick Release Design; Fast Networks：GbE LAN; Extended Connectivity：DP, HDMI; Smart If you have a single GPU and no other expansion cards, you should be fine with using the lower NVMe slot If you need to use those PCIe slots,