Suppose your typical ATX motherboard (or similar) has X number of PCI-e slots. Is it possible to connect additional GPUs (or any PCI-e device for that matter) beyond X?
I've seen a few solutions, however there's always some sort of 'but'. PCI-e backplanes require a special host board and become costly. External cards connected via a dock simply use an existing PCI-e slot anyway and don't actually increase capacity.
Basically, is there a way to split the PCI-e slots/lanes. If a x16 device can work as x1, is it possible to use the rest of the idle lanes for additional devices? In a gross oversimplification, an analogy would be like a USB hub.
In my particular case, I'm trying to get about 10 GPUs on flexible risers for farming purposes, so bandwidth and spacing isn't an issue.