GTX 970 4GB VRAM Issue
25 January 2015
The GTX 970 is a very popular GPU, so recent claims from some users that it is effectively limited to 3.5GB of its VRAM, and starts to suffer when using all 4GB, have caused a lot of concern. Nvidia's
official response confirms that there is a segmentation of the 970's VRAM between a 3.5GB section and a 512MB section, but that this has no performance impact. I decided to test this out for myself. Running Far Cry 4 at settings just high enough to use around 4GB of VRAM (3,840x2,400 via DSR plus all other settings to maximum, except SMAA) resulted in expectedly lower framerates, but no significant stuttering or hitching as demonstrated in this
YouTube Video. See this
Screenshot from the video to confirm that 4GB is being used - zoom in on the top left, second entry on the second line of the Afterburner overlay. Unfortunately some people have been "testing" this issue by using system-crippling settings, such as 4K resolution combined with 8x MSAA, and blaming the inevitable 5FPS slideshow on the VRAM. Quite aside from the fact that no current single GPU performs well at those settings, remember that slow or insufficient VRAM manifests itself as severe hitching (longer pauses) and stuttering (frequent brief hiccups), not an overall reduction in FPS. I did notice in my testing however that the GTX 970 definitely prefers using only 3.5GB of its VRAM in most cases; in the VRAM-hungry Watch Dogs for example, as settings were raised the 970 remained stuck at ~3.5GB VRAM usage right up until 8x MSAA was engaged at 4K resolution. After several hours of testing though my conclusion is that there's no discernible practical impact from this issue: the GTX 970 performs smoothly, whether using 3.5 or 4GB of VRAM. If you're experiencing stuttering or low framerates on a 970, in my opinion it is quite likely due to a general system issue or excessive GPU load, not VRAM segmentation.