Build It: Three Radeon HD 7970s—One Monster PC
Adding a Fan
The Switch 810 has a decent array of stock fans, but I have three GPUs super-heating the air and I want to make sure they’re adequately ventilated. I really like the pivoting fan mounts on the backs of the two hard drive cages, but only the top one has a fan preinstalled, so I’m going to add one to the bottom cage, as well.
Remove the thumbscrews at the top and bottom of the drive cage and pull it out of the chassis. Use fan screws to install the fan into the mount—only the top two mounting holes will be used.

Adjust the fan so that it’s pointing up where the GPUs will be and reinstall the cage into the case. Run the fan cable behind the motherboard tray and plug it into the fan controller there.

Installing all the GPUs
Because they take up so much room in the case, I installed the GPUs last—after I installed the DVD burner, hard drive, and SSD, after I mounted the PSU and connected all the power cables, even after I connected the case’s front panel connectors.
Install the topmost GPU into the topmost x16 PCIe slot, then the other two in order. You should have three PCIe power cables from the PSU, with an 8-pin and a 6-pin power connector on each. Connect one cable per videocard, making sure to power both the 8- and 6-pin connectors on each card.

Use one CrossFire bridge to connect the first and second videocards, and another to connect the second and third, as shown.

Next up: Benchmarks and conclusion!