Mini-ITX, microATX, Standard ATX"
It's not officially supported. You might try fitting it in, but right below the mobo plate, there's some outward protrusions where the PSU goes. It'd hit that. Between the 200mm fan at the top and the motherboard plate, a 12" inch cold cathode just barely fits (sideways of course! lol.)
You should simply take dimensions and measurements. If it can fit in the motherboard plate area, you can hang it by two or three screws. I have a small BIOSTAR board, and it doesn't align 100% with all the holes, not the ones at the top, and I can't screw them in due to a gigantic cooler, but surprisingly 3 screw holes at the bottom have held it in for like a year. It's never gave way or shown signs that it's only being held by 3 screws. The holes themselves sort of "connect" onto the support where the screw would go into, so even if it's not fully screwed in, that alone holds it real well in my experience. So long as it doesn't hit the PSU area nor the void between the mobo and the 200mm fan, it should at least mount onto at least a few screw holes.
@ 4-way CrossfireX or SLI
The Dragonrider case also claims to have the bracket shields/expansion slots necessary to support a foursome of cards, taking in mind that each may take 2. So of course 8 shield brackets divided by 2 =4 cards.
But on youtube, I saw someone claim that some cards are so massive, you will in fact need 10 expansion slots, worst case scenario.
Hmm.... I can see 6 shield brackets in the back of my case barely although there's 8, because my GTX card takes 2 expansion slots.
My GTX 460 Cyclone by MSI OC Edition takes up 2 shield brackets, but its fan's orb-styled zalman-esque heatsink practically hovers an atom off the next PCI 2.0 slot.
I think besides just the matter of the antec 902 v3 having all 8 brackets to support 4 way "in theory," you should also consider the dimensions of the card and its own heatsink. And how far apart the 4 PCI 2.0 slots are on your board. The GA-X79-UD7 slots have beautiful distance between each other though, and all 4 should fit handsomely.
An ideal upgrade option would be a full tower case, such as the Antec 1200 V3.
Would be, if it didn't cost half of our ***.