We posted an article about GTX970 memory performance issues earlier this week and it looks like NVIDIA are currently working on a driver update to try and fix these issues.
An employee on the company forum said that they are working to address issues when the graphics card begins to use more than 3.5GB of the allotted 4GB VRAM that it has available.
PeterS said that they will "tune what's allocated where in memory to further improve performance." It is important to note however that although the driver update will fix some of the issues it won't completely solve the problem. The software won't be enough to fix the flaw in the memory allocation and so there will always be slower memory performance in the last 0.5GB of VRAM.
He went on to say that if this issue is really affecting you so much then you should just return the card to where it came from and get a refund.
If you don't want the card anymore you should return it and get a refund or exchange. If you have any problems getting that done, let me know and I'll do my best to help.
The issue is only affecting those that run games with textures over 1440p resolution and the performance difference is only very minimal. It is around 3% compared to the first 3.5GB of VRAM so you may be running at 1-2fps lower than normal, which isn't that big of a deal.
Thanks, PC Gamer