> Yeah, but what I meant above was that if you only have an x4 slot electrically, sticking in an x16 -> 4x M.2 riser isn't going to do a whole lot, because the

> Yeah, but what I meant above was that if you only have an x4 slot electrically, sticking in an x16 -> 4x M.2 riser isn't going to do a whole lot, because the 12 lanes of 3 out of 4 slots aren't hooked up to anything. So in this scenario you'd really want a riser with a switch in it instead (which are more expensive than almost all motherboards). True; but given how PCIe speeds are no longer stalled, we may soon see motherboards offering an x4 slot that can be operated as x1x1x1x1. Currently, the only risers you're likely to find that split a slot into independent x1 ports are intended for crypto mining, and they require switches. A passive (or retimer-only) quad-M.2 riser that only provides one PCIe lane per drive currently sounds a bit bandwidth-starved and wouldn't work with current motherboards. But given PCIe gen5 SSDs or widespread availability of PCIe-native hard drives, those uses for an x4 slot will start to make sense.