Can I Use a PCIe NVMe SSD in a PCIe Motherboard Slot?

7PCIe slots Up to300Wauxiliary power One PCIe x4 gen 3 Apple IO card Four PCIe x8 gen 4 Two single height Two double height Two PCIe x16 gen 4 Double

The one where there was a Boot Drive, is actually Gen3 slot I thought that he installed on the secondary slot The terminology is, in the

candy bonanza slot demo If you can put up with the slightly nutty presenter, someone on Youtube did a video comparing these two drives on PCIe

can you own a slot machine Well yeah but if you put this card in an 8x slot then only two of the SSD's would work Wouldn't it just fall back to PCIe 3 speeds?