Why do you doubt that?
Stated measurements is 170mm x 140mm for the board. The cube is 248×195×195 mm excluding the acrylic shell.
I saw nowhere mention of it being inner dimensions for the cube, so i thought it was total; but anyway, consider the blank space between the plexiglass and the inner chassis, the chassis itself, the height of the whole chassis is around 2/3 of the total cube. Then, you have to figure the jacks for key/mouse, video etc. sticking out of the mobo. This would be a tremendous mod, one that would anyway involve unsoldering jacks from the mobo, and most likely drilling, cutting etc. on the cube itself...
This pic might give an idea of the situation:
