For a long time we had expected Intel's new Comet Lake-S CPUs to support PCI-Express 4.0, but then Intel nixed those plans. Then, we started hoping that its successor, Rocket Lake-S would get PCI-Express 4.0 support, and there appears to be hope. The chips at least are expected to feature PCIe 4.0, and motherboard vendors have also prepped their boards to support the interface.
But up until now, there hasn't been any concrete proof that it will actually happen, and there is still a chance that Intel will nix PCIe 4.0 on Rocket Lake-S, too. But for now, a SiSoftware entry has been spotted by Gonzalo (known on twitter as @Tum_Apisak) where a Rocket Lake-S system can be spotted running on a PCI-Express 4.0 interface.
So there it is. These entries aren't easy to fabricate, and this seems to be the proof we've been waiting for. It doesn't show a graphics card running over PCIe 4.0 yet, but as the storage system, it's quite a solid start.
Of course, we have to note that it's still very possible that the plans will get nixed, just like on Comet Lake-S. Just because something works early on in development doesn't mean that it will stay this way for the final consumer end-product. However, given that there are a ton of pointers to PCIe 4.0 working on Rocket Lake-S, we're gaining confidence that Intel won't get cold feet this time around.
The Rocket Lake-S platform is set to drop into the same Z490 motherboards as Comet Lake-S chips do, but will come with a whole new architecture. This is the same Willow Cove architecture Intel is using on Tiger Lake, but then backported to 14nm. This will limit the maximum core count, as Rocket Lake-S is expected to max out at eight cores, but they've been spotted boosting to 5 GHz, which paired with a new architecture would mean incredibly solid single-core performance, and that's what games are after anyway.
Meanwhile, we still don't know when Rocket Lake will land, but we can count on it being quite a while.
It was planned and cut too late for motherboard manufacturers to remove support from completed designs.