For gaming, not necessary. OTOH, if I'm going to put a 1080 GTX, 2 Xeons or $1700 single-proc, 32-64-128GB RAM, lots of SSD, etc. into a box, I sort of want to

For gaming, not necessary. OTOH, if I'm going to put a 1080 GTX, 2 Xeons or $1700 single-proc, 32-64-128GB RAM, lots of SSD, etc. into a box, I sort of want to make it dual-use. Option B is just getting two boxes and multiple inputs on monitor/kvm/etc.