having used
the onda j1800 six slot
the onda b250 8 slot + 4 riser
the k17 8 slot no name
here is what I have found all of them are great with evga hybrid cards or msi sea hawk cards
these cards look like this
if you do not want water block all the boards are spaced too tight and need more fans
the onda b250 has the most space and can do 6 of these cards set to 200 watts using a high end atx like a corsair.
http://www.corsair.com/en-us/hydro-gfx-gtx-1080-ti-liquid-cooled-graphics-cardI know this because I am running one at the solar array
The k17 can use a server psu which is nice it spaces a bit tighter then the onda b250
it can do 8 1080ti's using a server psu but you must wire the board correctly or you will kill everything
in order to do 8 1080 ti's you need the 2400 watt delta and you need 24 pcie cables
feed 8 six into the board from the server break out board.
feed 8 six pin into the six pin jack on the gpu use the server break out board
feed 8 eight pin into the 8 pin jack on the gpu use the server break out board
set tdp to 200 watts. it will not melt the board.
if you use the feed through option on the k17 and exceed 800 watts the board fucks up.
this took me a long time to figure out.
at the moment I use 5 hybrids. if you case this board it will need a lot of high power fans to cool off the gear.
and I would not use the feed through on all eight cards.
I do believe I could get 8 1070's to run in the ops case safely .
the onda j1800 has the highest spacing
I got 5 1080 ti hybrids to work doing 200 watt each 0 issues
In all my setups If i pack the cards in I use hybrids