Ok now to discuss memory and why 99% of folks are wrong. Resolution size has very very little to do with direct memory utilization. Its texture size that matters, and that is only loosely correlated with resolution. Modern games are being HORRIBLE with this by just shoving 4k textures along with the generated 2k, 1k and 512 versions into memory without checking if it actually needs them.
Most textures are rendered at 256 or 512 because they are at a distance and there is much less then 256 or 512 pixels of screen space to hold them. 4k textures would only matter if you were face hugging a wall with that single texture. Because of this there is virtually no difference between 1k and 4k textures at any resolution under 16k. So instead of pulling a crysis and clicking "ultra max optimized" just drag the texture detail slider down one or two notches.
Updating with more information as I'm back on the computer and not using a phone. If we stop and think about it, most textures on the screen are measured in hundres of pixels at best, a model of a robot we are shooting at might contain hundreds of textures, each relatively small. The final screen space for a single texture may only be a 20x30 rectangle or 600 pixels. Storing that texture at 4096x4096 pixels, or 16.7 million pixels is extremely wasteful. Never mind that we are also storing a 2048x2048 and 1024x1024 pixel copy along with it (some engines only store two down, others three down). Sticking with a 2048x2048 or 1024x1024 version of that texture would get is the same 20x30 rectangle, but a quarter of the memory requirements. What makes this even more wasteful is that game engines don't even bother using the 4096x4096 stored texture anyway, it just gets down sampled to a 256x256 or 512x512 prior to being rendered at 20x30. Modern games are, quite literally, filling GPU's with gigabytes of worthless data they don't even bother using, just to pretend to be the next "Ultra HD" video game.
Like how would everyone react if a game used part of your GPU to calculate prime numbers with each frame, then threw the answer away? Yeah that's basically what they are all doing with your GPU memory.