- Asrock B450 Steel Legend AMD : x6pcie (2x16slot + 4 x1slots) + 2m2 nvme slots
- MSI B450 Gaming Plus Max : x6pcie (2 x16slot & 4 x1) + 1 m2 nvme slot
Thank you, this is the answer I was looking for. We can add the Asus B450-F Gaming to the above list as well, since that too has 6 PCIe slots.
B450 chips however will only let you use one of the two m.2 slots while the 6 PCIe slots are populated, so that brings us to a total of 7 on these boards.
That appears to be the limit for now - 7 GPUs. Untill we switch to Intel and factor in 1x4 PCIe splitters.
What "gaming" mobo needs that many? Seriously you won't get any more because that's all that will fit the
form factor, not require risers, and provide rear panel access for monitors. Whichever way you go make sure
you get a real Ryzen that doesn't reduce the available PCIe lanes.