In a video posted on his YouTube channel, Brazilian-Japanese performance tweaker Faster shows how to work around the 4-Way SLI limitation for the GeForce GTX 780 imposed by Nvidia. The video is in Portuguese so unless you're fluent in that language, you will have to rely on the video instructions to get 4-Way running. From the looks of it, the newer drivers featuring support for the GeForce GTX 780 cards also include a couple of lines preventing it from running 4-Way SLI. The older drivers have no such limitation, but also don't officially support the GTX 780. By simply using a modified nv_disp.inf, you can add the support and enjoy 4-Way SLI. The process is actually quite simple:

1) Download the GeForce 320.00 BETA driver from Nvidia

2) Extract the driver content using WinRAR

3) Replace the original nv_disp.inf with a modified one, which you can download here (click)

4) Go back in the extracted driver folder and start the installation setup

5) Enjoy your GTX 780 4-Way SLI!

All credit goes to Faster from the Fusion-OC team. You can see his routine in the video below. Check out his forum thread here and here (Portuguese). With 4-Way SLI enabled on the GeForce GTX 780, Faster managed to score a solid 12,867 in Fire Strike Extreme.