So the World of Warcraft crowd> Who's trying to use NVMe downstream of the PCH?
Mostly DIY prosumers who buy motherboards with
2 x M.2 slots, or 3 x M.2 slots, and configure those
multiple M.2 SSDs in a RAID-0 array.
ASRock has a motherboard with 3 x M.2 slots:
The ASRock Z170 Extreme7+ Review: When You Need Triple M.2 x4 in RAID
Problem is, those multiple M.2 slots are ALL
downstream of the DMI 3.0 link on ALL
of the latest model motherboards e.g. Intel Z270 chipsets.
So, if you know where to look, a RAID-0 array
of 2 x Samsung 960 Pro SSDs topped out at ~3,500 MB/second,
and a single Samsung 960 Pro SSD was not too far behind,
because all were downstream of the DMI 3.0 link.