Here is another rig that lets you build a powerful system to mine cryptocurrencies. The Hydra III 8 GPU Rig can support coolers up to 330mm in length, 150mm high. It has space for 8 graphics cards and works with 19 inch server racks and rails.
The Hydra 3 places the motherboard and PSU behind the cards to give you more space. You have the option to install 3 x 120mm + 4 x 80mm high RPM server fans.