Video card RAM usage was interesting in Far Cry 4. Our results seem to indicate that there are VRAM limits depending on the resolution and settings. We weren't even using MSAA or TXAA and even with just SMAA the VRAM capacities were being hit by some video cards.

We found that we could hit the VRAM capacity on the 3GB GTX 780 at 1440p very easily. It seems 3GB is going to be limiting for 1440p gaming in Far Cry 4. With the two 4GB video cards these did not hit VRAM capacity at 1440p, at least with SMAA. If we had turned on MSAA these surely would have.

At 1080p it looks like 3GB is where you will want to be for the best experience. More can be better, if you want to run MSAA for example, but with SMAA and the highest in-game settings we didn't exceed 3GB.

At 4K the demand is going to increase beyond 4GB if you wish to run Far Cry 4 at the highest in-game settings. Given the proper performance, a 4GB video card is going to be a bottleneck running the game at the highest settings. We are talking Ultra Shadows, HBAO+, Enhanced Godrays, the works. We are guestimating that a 6GB+ video card would be optimal for 4K gaming at the highest levels.

Therefore, our recommendations for the best gameplay experience in Far Cry 4 are: 4K = 6GB VRAM, 1440p = 4GB VRAM, and 1080p = 3GB VRAM. That should allow a good experience with SMAA and "Ultra" settings.

We cannot explain why, across the board, the AMD Radeon R9 290X video card is filling more of its VRAM at every setting compared to the GeForce GTX 980, but likely due to compression being done more efficiently. If you recall compression efficiency is one that that was touted at the GTX 980 launch.