ue4 renders the next frame based on the previous,limiting use of multiple cards. To get around this, I intend to have multiple graphics cards act like a singular virtual card. is this possible?
Not really.
Unless you are making the cards and develop the hardware and drivers to make it possible. Most notably, the first card is the buffer limit. so having 2 cards in SLI doesn’t mean you have double the memory when it comes to the editor.
SLI for final games IS possible as of .16 - the benefits of it are near 0. And again, you get none in editor, so you have to publish a final product and benchmark it to get performance info.
somewhat unfortunate, but it never hurts to try