Can I Use a PCIe 4.0 Graphics Card in a PCIe 3.0 Slot? - TechReviewer
AMD's platform for Ryzen 3000 also ushers in PCIe 4.0, the first big change to the PCIe interface since 2010. Here's what you need to know.
XPS 8940, two ram slots not working | DELL Technologies
Not a solution but a work around - put a larger RAM module in the working slot to increase memory to what it was.
PCIe 4.0: Everything you need to know, from specs to compatibility ...
But what is PCIe 4.0, and how is it any better than PCIe 3.0 ... We'll walk you through everything you need to know, slot by slot, in this complete reference guide to PCIe 4.0.