I have a system with multiple video cards which are supported GPUs. Will this accelerate my 블랙토토 workflow?

The short answer is, unfortunately, no. For 블랙토토, installing more graphics cards will not accelerate further 블랙토토 workflows. It may slow you down due to slower CPU-GPU data transfers as the PCI Express bus will be shared and the PCIEX16 slot will operate at up to x8 mode.