Hi Marco and Jerry, it’s a very real problem if you start working on complex scenes where you are using a lot of 4k textures particularly. On lighter scenes or scenes where you have just a few models where the scene is under 3.5gb of video memory consumption then the 4gb GTX 970 will render much faster than say a 4gb GTX 760. However as soon as you build a detailed character, rig it, place it in an environment of any detail etc. it’s quite likely you’ll exceed 3.5 gb memory usage and then the card will run slower than the 4gb 760. I recently purchased both for some rendering boxes we set up for a project with characters and space scenes and nearly all our scenes just tip over the 3.5 gb memory usage and we’ve found that the GTX 760 will render a frame in 3.5 minutes on these complex scenes because it has a true 4gb limit so the card performance doesn’t clip, and the GTX 970 will dramatically reduce in performance on exactly the same file and will render the same frame at over eight minutes.
So our experience of this is that the more expensive card with more CUDA cores the (4gb GTX 970) takes more than two and half times longer to render the same frame as the 4GB GTX 760.
There’s a petition at change.org signed by over 10,000 Nvidia customers highlighting Nvidia’s dishonesty and fraud in the marketing of the GTX 970 as a full 4GB Vram graphics card. It isn’t. Nvidia deliberately downgraded the Vram on the card to compromise it so that the GTX 970 performance wouldn’t match the GTX 980 and their whole campaign on the GTX 970 has been false advertising throughout.
Shocking interview with Nvidia Engineer about the 970 fiasco
In terms of how many 4k textures it takes in your scene before this becomes an issue and notwithstanding all the other factors like scene geo, rigs etc, we ran into problems where we had a 4k scene background, 2-3 4k maps on built scene geometry and about 4-5 4k maps on character and foreground elements. When you consider a character that’s detailed where you want to keep the scene geometry low may only be 15 thousand poly’s but you may have a 4k displacement map, a 4k normal map, a 4k color map, then even if you make your other maps (specular, ao etc) 2k to try and bring down texture usage, it doesn’t take many image maps to see where having a 3.5 gb limitation on what is sold as a 4gb card becomes an issue.
A couple of people on other threads on Blender artists have dismissed this saying “it’s a first world problem, who cares” or “who uses that much Vram anyhow”. Those comments are pretty stupid and dismissive. The point is you bought your card for it’s supposed 4GB headroom and the future proofing that may have given you. And this problem affects many many people who do use and need the full 4gb Vram, from gamers to 3D artists.
If anyone considering buying a card for 3D work reads this, you will probably be frustrated with this card when you build a scene of any complexity and it’s definitely better to either opt up for a 980 or find a GTX 760 Ti on ebay. Even the standard GTX 760 4gb version (not GTI) will outperform the GTX 970 by a huge margin on any scene of any complexity. i.e If you are serious about 3d work and need a card that renders well, avoid the GTX 970.