You won't able to fit all 4 cards in a case on motherboard without using risers, because it will cover the next pcie slot and you can only able to fit 2 cards in a case.It's a three slot card.
I though it was a dual-slot design or is it 2.2 slots? The ASUS R9 280X DCII would be my next choice or would the Gigabyte WindForce be better?
they are dual slot, you can fit four without the risers, just try to keep the temp low as a possible