also is there a chance you will make a rig that supports 2 motherboards?
and i would also suggest putting a small mounting plate behind the motherboard for the psu instead of using up precious space for gpus.
We answer both those questions in the FAQ tab on the product page, here are cut and pastes for your reference:
Why is the PSU mounted on the side and not underneath the GPUs?We spent a lot of time testing various configurations, including rear-mounted offset PSUs, vertical motherboard mounting, and so on. We ended up with the following requirements: PSUs need to be easily accessible, all configurations need to support dual PSUs, and regardless of whether a single PSU or dual PSUs are mounted there should be no airflow deadzones or unusual hotspots. The design we ended up with met all those criteria.
Can I mount two motherboards on an 8 GPU rig?No, it's not designed for that, and that sort of configuration doesn't promote easy access to hardware and doesn't fit in with our design ethos. You are, of course, welcome to do whatever you want with it once you receive it, but we'd prefer customers opt for a horizontal row of Arianna grid frames than trying to re-purpose something.
Bottom line: we're not in the business of shaving a few cms off for a design that puts out customer's equipment at risk. Our designs are reasonably space efficient (I mean, look at their dimensions, it's barely a footprint) whilst ensuring excellent airflow with no dead zones.