I have to disagree,
i have seen quite a few downvolted SFF builds. This does not make sense to me, or to corsair (one) or digitalstorm (bolt) and it isindeed a much more important compromise than size for many.
A small custom loop is both powerful and, well, small. It does not have to be the smallest otherwise we would all buy mac minis or ARMs.
It should tick all boxes, and if while doing so you need 380mm length then so be it.
A professional could render on the go, without (IMO) reducing by some % his performance while spending the full amount of money. Gaming on a small desk sitting the case horizontally under the screen...
By exploiting hardware i mean overclock it, squeezing as much performance per dollar as possible
380x220x140 is not a niche case, especially for around 150$. (obviously these are very rough guesstimations). Lessons about this come from Ncase, NZXT, LianLi.........
Look at Sliger SV590, getting reeeeeeeeeeeeally close to it
without radiator it could also become a 6x120 (3 in 3 out) fans case... also a very good air cooling option
Hope to get some constructive and peaceful discussion going, peace and love
The niche case is that you'd have to be both a custom water cooler and an SFF builder. It wouldn't make business sense because you need to invest a lot of money and time and your addressable market is small.
It'd be impossible for $150 out of metal unless you're direct out of China. Made in USA or a proper manufacturer it'd be for at least $220. Even sliger who directly owns all the capital to manufacture the cases sells them for as much. But even then, price wouldn't really be a hindrance, since if you're custom watercooling, especially a small specialized build, you'd be spending a lot on the loop and you'd have a lot of experience.
Concerning undervolting it makes the most sense. Undervolt is tuning for performance/Watt. Since cooling capability is correlated with volume, and we're all about going smaller, then why would you leave performance/Watt in the table?
Sv590 works because it is designed for AIO and regular gpu, not a custom loop, though there is space for it.
A 280mm makes more sense. Close in performance with 360, and the dimensions would match components better. Even when rendering, you often don't saturate both gpu and cpu at the same time.
But I'm not saying the idea is impossible, just that it'd be tough to sell a pure water cooling case. If it's solid and has merit, then someone should invest in it.