I've read that CPUs have PCIe lanes and that those are used by the GPU.
1.- So if Ryzen 2700x has 20 PCIe lanes, does that mean I can only have one x16 GPU (or 2 x8)?
2.- Does that mean if I want two x16 I need a 40 PCIe lanes processor?
3.- If that's the case, why does having multiple graphics cards on a 20 PCIe lane CPU actually makes a difference while GPU rendering?
(About the third question, here's a post showcasing it)
4.- If it doesn't affect negatively having multiple graphics cards on a 20 PCIe lane CPU (such as Ryzen 2700x) while doing GPU rendering, then, when does it matter? (negatively)