Originally Posted by CynicalUnicorn
Typically you use mITX for HTPCs, so I would say no on the SLI, unless you want to make a compact mATX case. You'd only need one 5.25" bay for an ODD. That and two each 3.5" and 2.5" drive cages should take care of that. Add one 5.25" bay and two 3.5" bays if you go mATX. If you want quiet, then you should be able to fit the biggest fans possible on the top and front, 200mm would be best if there's room. Go with a bottom-mounted PSU if possible so its center of gravity is lower.
should be possible to make a case that is compatible with both mITX and mATX boards. This would leave extra room for other goodies if one wanted to go the mITX route, but also leave room for the guys building a gaming rig.
If you make a taller case, with HDD racks at the bottom, you can set the case up so that it can hold maybe a 2x120/140 mm rad or even a 360 radiator in the front... or just fans if the user so chooses. This can also serve to make the case shallower from front to back, at the cost of height... of course this height will already be there is a standard size PSU is to be fitted, but will limit you to 3, maybe 4 HDD bays.
You can then stick a single optical drive bay at the top.
There are lots of options to compact a case, I personally like the idea of NOT using traditional front mounted bays. I think it makes cases too big.
If you design it like that, you can also leave maybe a knockout or even just put a fan in the top as well. This could house another 120 or 140mm fan/radiator.. with a little extra height, and a little extra depth, both the front and top rads could be mounted internally.
It really depends on what you want. You cant have a truly universal case design that is very compact, and you cant have a truly compact case that isn't built for one very specific layout.
I have a very compact design that allows a full size motherboard, a 140mm radiator (NZXT Kraken AIO to be specific), two air cooled cards in SLI, and has enough airflow that I have faith it would stay cool. However, it is designed purely with the large spacing between the pci slots that my sabertooth provides. Not all motherboards offer an extra slot in there for air cooling two cards. This would not work with many other boards because of it.
My design is somewhere around 14x14x8", though I can't recall the exact dimensions off the top of my head.
Unfortunately I cannot post the image, as the image thing doesn't work with our computers here at work.. If you PM me I will be happy to share all my pics and the design with you later.