It might be my mistake. As always, Corsair does not properly put Technical Specifications on their website. That is a thing I really hate about their website. There it is said that 900D has 15 possible fan spots. Judging by pictures, I tough it was 92.
And as I said "and 15 92mm (i guess, not specified on Corsair webpage)" - it is a guess.
Even so, that is extremely bad for a case of this caliber. I would (and many more) gladly ditch all 92/120 mm fan spots for 140/180 and best is 200mm fans.