unless you use a riser or undervolt the cards the temps will rise or put a fan in front of them to keep the temps a bit lower.
When you mean a fan, you mean a "real fan" outside the chassis ? Or some fan in front of them on the chassis ?
Because, the Corsair Carbide 540 has two large fans in front of them, that's why I chose this one (and thought clever about it
.. clearly I was wrong )