GTX 970 performance issues: the good, the bad and the ugly
Whether you have a gtx 960, a gtx 1060 or one of AMD's Radeon R9 290 cards there's still plenty of reasons to upgrade to a newer GPU in 2019; they offer better performance and more VRAM at much lower price points. For those looking for the most cost effective solution the gtx 970 FTW is still a great choice but it's not as good as you might have thought.
The problem is with the last 0.5GB of memory on the card. NVIDIA divided the card's 4GB of memory into two pools to reduce the number of ROPs on the GPU, the 3.5GB section is optimally accessed and managed by the operating system while the remaining 0.5GB is slower (though it's still faster than PCI Express or system memory accessed via the motherboard).
While Nvidia has tried to downplay this issue by telling us that the performance drop when using the second pool of gpu memory is only in the mid single digit percentages some users have reported more significant framerate issues when accessing the second pool of memory. Nvidia's Jonah Alben explains the details behind the issue in a recent forum post.
He explains that peak bandwidth will remain at 224GB/s despite the division of the memory controllers but only when the card is able to access both pools simultaneously. He also explains why the second pool of memory runs slower than the 3.5GB section and tries to dispel some common misconceptions about this particular issue.