Hey guys I recently upgraded my GTX 780 Ti with a GTX 980 Ti. I have cut out 4-6 seconds by installing both gpu's at the same time for premiere cc renderings (compared to just the 980ti). I wanted to know if the difference in VRAM will affect performance (3GB vs 6GB of VRAM). I have only tested this out 5D3 footage.. Will this be similar to SLI/CrossFire where I will only be able to take advantage of 3gb of VRAM?
Why don't you test it yourself. Get GPU-Z and run and monitor both simultaneously (two instances of GPU-Z) . Look at the sensor tab to see VRAM usage and the real memory clock speeds. I have been wanting to run an experiment with two boards with different amounts of VRAM and then reverse the PCIe bus locations and see if it made a difference. With your 5D3 HD footage it might not really show much difference. Now with 4K media it might be more significant.
With you GTX 780 Ti you can overclock the memory and achieve additional performance with it. With the GTX 980 Ti you will see it automatically lower the memory clock anytime you run a CUDA application like Premiere.