Fractal confirms stability issues with PCIe 4.0 riser in Ridge case – Computer – News

For anyone who says, “why are motherboards so expensive these days” — here’s why.

PCIe 5, and also DDR5 are absurdly tight in terms of timings. Even with multiplexing (which makes signal quality even more important) the timing requirement is so high that the length and quality of a PCB is already a limiting factor, let alone the length and quality of a riser cable. PCBs simply have copper tracks with zig-zag patterns to make the length of the inner bend the same as the outer bend, while EMI must be avoided at all costs.

This is the umpteenth PCIe 4 riser that doesn’t work well, and the umpteenth time we hear (sometimes even without a riser): “put your board on a lower PCIe standard because then it will work”. We’re lucky that PCIe is backward compatible in both directions, but there will come a time when the biggest advantage of PCIe (more bandwidth per lane) translates to devices with fewer lanes (mid-range/low-end GPUs are already with only four lanes connected), assuming that a high version works so there is no impact, and a message like: “go back to old PCIe standard” translates into a noticeably worse experience.

I can identify with companies like Dell coming up with CAMM. DDR5 is simply much faster “on-die” than when jobs have to go through a socket over a busy PCB to a DIMM slot. High-end overclocking boards with CPU sockets and DIMM slots rotated by 90 degrees are also becoming more and more common, and daisy-chaining is completely taboo, as you increasingly read here on GoT that the solution to “XMP is not working” is to replace the memory of lock (A1 to A2, etc…). And then a few years later the frustration that the QVL is more important than EVER, because more dimms (which have only become more difficult in recent years), and speed is not a good combination.

TL;DR: This is very unfortunate for Fractal, and for PCIe gen4 “needs” who also want vertical.

But for the PC market per se and more importantly (for me then): DIY fans — an alarm bell. With the tight timings that are required, I can imagine that an entire PC including a high-end GPU will soon no longer be modular, due to the absurd signaling that is required.

Wonder if and when we’ll ever see PCIe 5 risers (although GPUs will take a while, SSDs will go to PCIe5 first)