Nvidia never saw fit to release a version of its previous generation GeForce RTX 2070 with 16GB of video memory, even though leaked schematics suggest it was both possible and planned at some point. Proving the former, someone took matters into their own hands and carefully modded a GeForce RTX 2070 with twice the memory.
It was the aforementioned schematic that prompted the modder, who goes by "VIC-on" on his YouTube channel (via Tom's Hardware), to attempt the delicate memory-doubling mod. Even better, he posted a video of the complete mod, which is embedded above.
The card shipped with 8GB of GDDR6 memory made by Micron. However, the schematic indicates the GeForce RTX 2070 also supports both 1GB and 2GB of Samsung-brand GDDR6 memory chips. Armed with that information, VIC-on tracked down a package of eight Samsung 2GB GDDR6 memory chips on Aliexpress, paying just over $200.
That is a pricey upgrade, but a mod like this extends beyond the realm of practical and falls squarely into proof-of-concept territory. It's certainly not like upgrading the RAM in a desktop PC or laptop, either. Rather than simply pluck out any modules, VIC-on had to use a heatgun to loosen the actual memory chips surrounding the GPU, and pried them off with tweezers.
Before installing the upgraded 2GB Samsung chips he purchased, VIC-on had to relocate a set of resistors on the backside of the printed circuit board,. This meant busting out the soldering iron. He then plopped the Samsung chips into place, powered up his PC with the modified card installed, and presumably crossed his fingers off camera.
It booted into Windows without issue. And when he fired up GPU-Z, the utility recognized the 16GB of Samsung GDDR6 memory. So far, so good. Unfortunately, it was not smooth sailing from there on out.
He tested the modded card with FurMark, a utility that stresses graphics cards. It appeared to run fine, but after exiting, the PC crashed to a black screen. VIC-on notes that this happens after any kind of load is put on the card, including gameplay.
There are a multitude of reasons why this might happen. However, he suspects the culprit is the BIOS. Specifically, VIC-on surmises the card trips up because the frequency and voltage table in the BIOS does not match up with what is now installed.
Regardless, VIC-on deserves major props for doing what Nvidia never did, which is double the memory on the on the GeForce RTX 2070. Even the current generation GeForce RTX 3070 only has 8GB of GDDR6 memory, and he intends on eventually modding one of those as well.