GPU maker Nvidia has responded to claims that its critically praised GTX 970 uses only 3.5GB of its 4GB of VRAM, resulting in performance drops or stuttering in games that pass over that threshold (usually those running at 1440p and 4K resolutions). In doing so, the company has revealed that the published specifications for the GTX 970 were partially incorrect, with the GPU actually sporting fewer ROPs and L2 cache than consumers and reviewers were initially led to believe.

Nvidia's Senior VP of GPU Engineering Jonah Alben spoke to PC Perspective about the issue, with the publication noting that "despite initial reviews and information from NVIDIA, the GTX 970 actually has fewer ROPs and less L2 cache than the GTX 980. NVIDIA says this was an error in the reviewer's guide and a misunderstanding between the engineering team and the technical PR team on how the architecture itself functioned. That means the GTX 970 has 56 ROPs and 1792 KB of L2 cache compared to 64 ROPs and 2048 KB of L2 cache for the GTX 980."

Nvidia's initial GTX 970 specs weren't entirely accurate.

While not a performance bottleneck in of itself (the GPU's 13 SM units, running at four pixels per clock for a total of 52, limit the GPU more than the 56 pixels per clock processed by the ROPs), the reduced number of ROPs directly affects the GPU's memory subsystem. Unlike the pricier GTX 980, the GTX 970's 4GB of memory is divided into two pools in order to accommodate the reduced ROPs: one 3.5GB section, and one 0.5GB section.

The result, it transpires, is that the 0.5GB section is slower than the larger 3.5GB section. However, it is still faster than system memory accessed using the PCI Express bus.

While this issue does not affect most games, those that feature large textures, or those that are ran at 1440p and higher resolutions may see a drop in performance. In a statement, Nvidia clamied this would be around a three percent drop. It's worth noting that Nvidia's benchmarks only looked at average FPS performance, which may not account for the frame stuttering that some users claim to be experiencing.

A Change.org petition calling for refunds due to the incorrect specifications has since been launched. Those interested in a more technical breakdown of the GTX 970's memory subsystem and performance troubles should check out the full PC Perspective story.