A Russian technician and modder known as VIK-on has posted a hands-on video showing how Chinese workshops are converting GeForce RTX 4090 gaming cards into AI-focused accelerators by doubling their memory. Using an MSI RTX 4090 Suprim as a donor, VIK-on removed the AD102 GPU package and the card's 12 2 GB GDDR6X chips, then placed those parts onto a custom clamshell PCB that accepts memory on both sides. The builders pair the board with a blower-style cooler, designed for multi-GPU racks, and load modified firmware so that the system recognizes the larger capacity. The method mixes factory-level board work with careful firmware changes and advanced soldering. You can purchase a brand-new custom PCB that includes clamshell memory support and has most passive components pre-installed. You can see it in the third picture below, the upper PCB is the newly bought one, the bottom one is the original. However, the GPU and memory must be reflowed or hand-soldered, which requires expensive tools and expertise.

Firmware mods, some of which trace back to techniques used for salvaging cards with faulty memory channels, are adapted to enable the GPU to accept the new layout. Shops often harvest GDDR6X chips from defective cards or purchase modules at a low cost, which reduces expenses, but the conversion process is still not trivial. Published price notes indicate that the clamshell kit costs roughly $140 in China, and the total cost of the parts for a DIY upgrade is near $430 before shipping.
Converting large numbers of consumer cards for AI reduces the supply for gamers, and stripped or modified boards can resurface on the second-hand market, surprising buyers. Additionally, modified cards may not meet reliability standards or all warranty rules. They can even malfunction under sustained workloads. Therefore, it is better to skip going after a customized GPU to save yourself the hassle of compatibility issues; however, the point that it can be done remains.