Riser board for the M90q with NVMe M.2 connector and much more

[radu.sctin]

I was trying to figure out if the BMC_DETECT will work out of the box or soldering will be needed like the previous generations and stumbled across this same thing. Discarded it for that moment but now reading your post it all makes sense. I have a feeling that this was intentional on their part...

Last night I was looking at possible solutions to this and there is nothing that I found that comes without a price...
1. Move to 6 layers and change the PCIe connector to SMD. This leaves space for cross routing but gets more complicated on the impedance calculations and the connector is more difficult to source (especially the open ended kind)
2. Use PCIe switches. Something like PI3DBS16412 but it takes 4 of them and also are not cheap or easy to source. Routing is also an issue so point 1 still stands. This would make the board more flexible though.
3. ???

I agree with the consistency across generations. Maybe the community can help us out with some hi-res board photos of those strapping resistors for different generations and models?

 

[WifiCable]

I think the best solution is not to try solving this issue in the riser, but just tell people to mask the pad on the CPU. It's relatively non-invasive and not an unfamiliar mod either, people were already messing with CPU pads for the bifurcation mods anyway.
That way the riser also won't break compatibility with potential future or random non-reversed boards.

I agree that it would be nice to have a large dataset of how the resistors are set on boards from the community. I reached out to ETA Prima on youtube since he had a x4 RX6400 working in an M90q Gen 3 with the x16 riser but haven't heard back yet.

 

[WifiCable]

Lol I just tried how bad it would be to reverse a x8 link, and it's actually not even that bad? It's possible with a through-hole slot and a 4-layer PCB. It feels like very evil routing but honestly I don't see why it wouldn't work:

(don't mind the low quality/cursed routing, it was just a test to see if it's possible)

 

[WifiCable]

It could certainly be a neat idea to offer a lane-reversed option for people who don't want to do any mods to the machine itself