After the whole controversy surrounding GTX970’s VRAM usage, NVIDIA went ahead and made a statement regarding this issue. According to the green team, GTX970’s memory is split in two sections; the first section that has a higher priority allocates 3.5GB while the second section allocates 500MB. And while a game can allocate all 4GBs, only 3.5GB are being allocated when a game needs less than that.
As NVIDIA’s forum moderator ManuelG claimed:
“The GeForce GTX 970 is equipped with 4GB of dedicated graphics memory. However the 970 has a different configuration of SMs than the 980, and fewer crossbar resources to the memory system. To optimally manage memory traffic in this configuration, we segment graphics memory into a 3.5GB section and a 0.5GB section. The GPU has higher priority access to the 3.5GB section. When a game needs less than 3.5GB of video memory per draw command then it will only access the first partition, and 3rd party applications that measure memory usage will report 3.5GB of memory in use on GTX 970, but may report more for GTX 980 if there is more memory used by other commands. When a game requires more than 3.5GB of memory then we use both segments.
We understand there have been some questions about how the GTX 970 will perform when it accesses the 0.5GB memory segment. The best way to test that is to look at game performance. Compare a GTX 980 to a 970 on a game that uses less than 3.5GB. Then turn up the settings so the game needs more than 3.5GB and compare 980 and 970 performance again.”
NVIDIA has also shared the following graph, showcasing games using more than 3.5GB of VRAM. Not only that, but the green team provided percentage numbers in order to prove that there is no major performance hit when the additional 500MB of GTX970’s VRAM are being used.
We do have to note that we’ve heard other users with older GPUs experiencing such “weird” VRAM usages. In other words, this is nothing new. Still, this is the first time this ‘weird’ VRAM behaviour came to light.
Bottom line is that by design, the card is allocating 3.5GB when a game requires less than that, that it can use more than that when a game requires more VRAM, and that there is no additional performance hit caused by allocating those 500MB of VRAM (do note that we are only talking about VRAM usage here, not about raw power performance numbers and framerates).