When you're looking to buy one of the best graphics cards, performance often ranks as the most important aspect (along with pricing for many of us, naturally) — check our GPU benchmarks hierarchy if you want to see how the various cards stack up. But lately, we're seeing more games that seem to need lots of VRAM, possibly 16GB or more. Star Wars Jedi: Survivor, The Last of Us Part 1, Warhammer 40K: Darktide, Hogwarts Legacy, Final Fantasy 7 Remake, Elden Ring... the list is getting quite large for games that can exceed 8GB or even 12GB of VRAM use, depending on your chosen settings and resolution. What exactly is going on, though, and how much VRAM do you really need?
Superficially, you might think it's just a case of higher resolutions naturally requiring more VRAM. 3840x2160 (4K) is four times as many pixels as 1920x1080 (1080p), and 2.25X as many pixels as 2560x1440 (1440p). But while that can dramatically increase the number of calculations your GPU needs to perform, on its own it doesn't actually make a game use that much more VRAM.
Games have lots of buffers these days. There are framebuffers, depth buffers, geometry buffers, buffers for shadow maps and lighting, deferred rendering buffers, and potentially buffers for upscaling techniques like DLSS and FSR2. There can also be additional storage requirements for ray tracing, like the bounding volume hierarchy (BVH) structure. Anyway, not to get too far into the weeds, but there are many things that need memory.
Those memory requirements scale with resolution. For the framebuffer as an example, going to a resolution that's four times higher will generally mean using four times as much memory. Doing that for each buffer seems like it might be a big deal. But when you do the math, it's actually not that bad.
Using a 1080p resolution means 8,294,400 bytes are required for each buffer (1920 * 1080 pixels, with four bytes per pixel). 4K quadruples that to 33,177,600 bytes, while the in-between 1440p requires 14,745,600 bytes. Suppose there are ten such buffers used in a game. The difference between 4K and 1080p would still only end up being about 237 MiB — and there may be real-time compression / decompression techniques present in modern GPUs that reduce the storage requirements for certain buffers.
Most modern graphics cards have at least 8GB of VRAM, so an increase of around 0.2GB in memory requirements shouldn't matter much. But if you've ever gone from running a game mostly fine at 1440p to seeing your graphics card choke at 4K, you know something is causing problems. It may not be the larger buffers causing issues at 4K, but there's clearly something going on.
(Side note: Nvidia let us know that it's current architectures do not compress the framebuffers, "based on cost/benefit tradeoffs." However, we're not certain if AMD GPUs compress the framebuffer or not. Other buffers may or may not use some form of lossless compression, depending on the particular buffer and application.)
