Just stumbled upon this while checking for "new posts": Chances are high you wont find any cases.
There is the Luna A2 with 8.2 liters and Flex-ATX PSU, maybe the SFF Time U-ITX.
Thats pretty much it.
For measurements, the longest parts are: The GPU, and the radiator obv.
GPU block length acc. to the Bykski US site is 234.9 =~ 235 mm. Depth is 26.57 =~ 27 mm, max width is 127ish, lets assume 128 mm.
Shortest 240s I know of run at 277 mm length, so lets go with 280 mm. If we want side panels of any type, we also have to add about 2 mm per side, so that gives us 284 mm in total length (excluding any protrusions of the GPU, IO ports etc).
Height is limited by the mainboard size, so 170 at least, lets add the panel size, so its at least 174, albeit I'd round it up to 180 mm to have a bit room to spare, eg. for cable routing.
Depth: 20 mm for the MB itself with enough space on the back left for air ventilation, not scraping off any chipsets etc. The CPU block adds 25 mm, but I'm very sceptical you could use the side inlet/outlets easily, so make that maybe 45 mm. Also there is the IO height, albeit that could be lowered by removing the IO shield. Still, 65 mm of depth, maybe 60 mm at best sounds reasonable.
PSU: Is slightly longer than the HDPlex GaN 500, sitting at 220 mm length,
according to the Supermicro website - aside of that almost identical dimensions (54.5 x 220 x 40.25 mm).
Lets assume you're going for slim rads with regular sized fans, so its 20.5 mm + 25ish mm, thus we assume 46 mm.
With slim fans, I'd pick the Air Slimmer 120, because of the most oomph, which sit at 15.6 mm - except if you get your hands on the unobtainium Thermalright Extrem _15 mm_ ones. So we're seeing a 20.5 + 15.6 mm = 36.1 mm, better go with 37 mm.
Sandwich layout would sit at 180 + 37 in height = 217 mm, 284 length and probably 27 + 65 + 4 = 96 mm in depth = 217 x 284 x 96 = 5916288 = 5.916288 L -
but thats without accommodating the PSU.
Now lets maybe place it underneath the GPU block, that'd either result in a height increase by at least 2 mm, and a depth increase of at least 9 mm, so lets go with that: 182 + 37 = 219 mm, 41 + 65 + 4 = 105 mm depth.
As mentioned before, maybe might be possible to go with 60 mm, so that'd be at best:
219 x 284 x 100 = 621960 = 6.2196 L =~
6.22 L.
Console layout: 170 + 128 + 41 (MB + GPU block + PSU) = 339 mm, lets assume we place the radiator on top of the GPU block, which should work because 240 rads tend to be somewhere between 118 and 124 mm in width.
Height would be at least 73 mm because there needs to be at least SOME air flow, so I assume at least 10 mm distance between rad + fans and the GPU block. Maybe 5 mm might work, too, but YMMV. That'd place us with:
343 x 77 x 284 (including side panels) = 7500724 =~
7.5 L
An "off the shelf" console-style layout might be possible with the
SFFTime U-ITX with a bit more optimization.
Traditional layout:
Depth: 127 + 20 + 4 = 151 mm, maybe 140ish because of the PCIe connector etc.
Height: 170 + 41 + 4 = 215 mm
Length: 284 mm (or 277 without panels etc.)
Even with more optimization,
its sitting around 8.5L.
cu, w0lf.
. Oh, and here on SFF.net we also got someone that 
