GPU-Z: An imperfect tool
GPU-Z claims to report how much VRAM the GPU actually uses, but there’s a significant caveat to this metric. GPU-Z doesn’t actually report how much VRAM the GPU is actually using — instead, it reports the amount of VRAM that a game has requested. We spoke to Nvidia’s Brandon Bell on this topic, who told us the following: “None of the GPU tools on the market report memory usage correctly, whether it’s GPU-Z, Afterburner, Precision, etc. They all report the amount of memory requested by the GPU, not the actual memory usage. Cards will larger memory will request more memory, but that doesn’t mean that they actually use it. They simply request it because the memory is available.”
When we started this process, I assumed that a number of high-end titles could readily be provoked into using more than 4GB of VRAM. In reality, this proved a tough nut to crack. Plenty of titles top out around 4GB, but most don’t exceed it. Given the lack of precision in VRAM testing, we needed games that could unambiguously break the 4GB limit.
We tested Assassin’s Creed Unity, Battlefield 4, BioShock Infinite, Civilization: Beyond Earth, Company of Heroes 2, Crysis 3, Dragon Age: Inquisition, The Evil Within, Far Cry 4, Grand Theft Auto V, Metro Last Light (original), Rome: Total War 2, Shadow of Mordor, Tomb Raider, and The Witcher 3: Wild Hunt. Out of those 15 titles, just four of them could be coaxed into significantly exceeding the 4GB limit: Shadow of Mordor, Assassin’s Creed: Unity, Far Cry 4, and Grand Theft Auto V. Even in these games, we had to use extremely high detail settings [@ 4k] to ensure that the GPUs would regularly report well over 4GB of RAM in use.
While we do see some evidence of a 4GB barrier on AMD cards that the NV hardware does not experience, provoking this problem in current-generation titles required us to use settings that rendered the games unplayable any current GPU. It’s reasonable to ask why we didn’t fine-tune results, attempting to measure the impact of just going over the 4GB threshold with the GTX 980 Ti or Titan X, and then test with those settings. Unfortunately, GPU-Z simply doesn’t measure accurately enough to make this possible.
The most we can say of a specific 4GB issue at 4K is that gamers who want to play at 4K will have to do some fine-tuning to keep frame rates and resolutions balanced, but that’s not unique to any vendor. If you’re a gamer who wants 4K and ultra-high quality visual settings, none of the current GPUs on the market are going to suit you. HBM2 and 14/16nm GPUs may change that, but for now playing in 4K is intrinsically a balancing act. The Fury X may require a bit more fine-tuning than the 980 Ti or Titan X, but that’s not grounds for declaring 4GB an unsuitable amount of VRAM in today’s games.
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