I have seen some mining rig with 6 gpu in one motherboard, can you use that for rendering?
1x 1200 Watt Power Supply
1x 6 GPU Motherboard
1x Skylake Dual Core CPU
1x 4 GB RAM (system memory)
6x Nvidia GTX 1070 GPU’s (6 of these, I like EVGA and Gigabyte) 1x USB Riser Cables (6 pack)
1x Solid State Drive (for OS / mining software)
1x Custom Mining Case