NVIDIA GeForce RTX 3070 mod confirms that there was a 16 GB VRAM configuration in development
The GeForce RTX 3070 may have 8 GB of VRAM, but it turns out that the Ampere graphics card supports up to 16 GB. Modifying a GeForce RTX 3070's VRAM is not for the faint-hearted, though. As the videos by VIK-On below show, one must be comfortable with removing the eight 1 GB modules that are pre-installed on the board, replacing these with 2 GB modules and altering certain resistors on the PCB.
These resistors are commonly referred to as straps, for reference. By default, NVIDIA sets these straps to 00000 bits for Samsung memory and 00001 for Micron memory. However, VIK-On found out that 00110 allows the RTX 3070 to run with 16 GB of VRAM. NVIDIA had been expected to release an RTX 3070 with 16 GB of VRAM at some stage. Nevertheless, in October it emerged that the company had shelved plans to do so. Since then, NVIDIA has launched the RTX 3060 with 12 GB of VRAM, adding confusion to its Ampere product stack where there need not have been any, in our opinion.
Hence, it seems that VIK-On has confirmed that NVIDIA was developing a 16 GB variant of the RTX 3070 at some stage. The modified RTX 3070 works too, albeit with some initial instabilities. Locking clock speeds in EVGA Precision resolved these instabilities though and allowed the modded RTX 3070 to outscore the RTX 3070 Founders Edition in 3DMark Time Spy and Unigine Superposition.
Ultimately, we can see why NVIDIA decided against releasing a 16 GB version of the RTX 3070. Currently, few games benefit from having more than 8 GB of VRAM, although some modern triple-A titles will come close to that ceiling. Additionally, the RTX 3070 is likely to run into other hard limits before it needs more than 8 GB of VRAM.