I am trying to find something that is exceptionally weird and bizarre. I want to use a M.2 NVMe x4 SSD in a PCI-Express x1 slot.
x4 NVMe SSDs directly use PCIe bus protocol, and so can be directly plugged into a full-size PCIe slot using a simple passive adapter. But there are four data lines, so these passive adapters are virtually all x4 lane cards.
By specification, all PCIe cards are backwards compatible with the lowest bandwidth x1 lane slots. If the x1 slot is designed with an open end, it is possible to plug a x16 card into it with 15 lanes hanging exposed in midair and unconnected, and it will work. It won't work well but it will work.
So, what I need is a NVMe x4 passive adapter card, which will plug the M.2 into a normal PCIe x1 slot, and leaves the remaining 3 lanes unconnected.
I have been searching the web on and off for months and have not found anything like this yet.