Over the last couple of weeks, several hardware forums saw claims from different users that NVIDIA GeForce GTX 970's slows down terribly when trying to access the 700 Mega Bytes of its memory.
It was quickly confirmed that some games halted whenever it used more than 3.5 GB on Geforce GTX 970. However, some other games – such as Call Of Duty – were able to fill the 4GB completely. Naturally, most people believed that the slowdown was due to some bug in the affected games.
But then a German programmer named Nai developed a small program to benchmark the RAM performance on GeForce GTX 970 and compare it to that of the GTX 980. The program showed clearly that that the GTX 970 RAM speed dropped drastically when accessing data beyond the first 3200 MB with no similar degradation witnessed on the GTX 980.
As seen in the screenshot in the gallery, GeForce GTX 970 normal RAM speed is around 150 GB/s but it fell down to around 20 GB/s when accessing data in the last 700 MB. On the other hand, the GTX 980 was able to keep a consistent 178 GB/s RAM speed across the whole memory space.
NVIDIA has acknowledged the problem and dedicated an "entire team working on this issue with a high priority." Unfortunately, NVIDIA was not able to find the cause of the problem at the time of writing.
