When an individual named "isoO", a member of the hardwareLUXX forum, took apart his RTX 3090 Founders Edition's cooler to attach some water cooling kit to it, he was surprised to see that his 3090's die was remarked to an ID that read "GA102-300-A1" from the initial ID "GA102-250-KD-A1". It is known that the 'GA102-300-A1' ID belongs to the RTX 3090 while the "GA102-250-KD-A1" was found to be a chip with the same core configuration but with a reworked memory interface (via @kopite7kimi) to accommodate 4GB less memory. Hence, while both the chips packed 10,496 CUDA cores, the 'GA102-250-KD-A1' variant would have 20GB of GDDR6X.
In fact, this wasn't the first GA102-250 chip that was discovered. A non-KD version dubbed the "GA102-250-A1" was also dug out by the same Twitter user about a week prior which had 9,984 CUDA cores and 12GB of GDDR6X memory across a 384-bit wide bus. It is possible that Nvidia was pondering between these two configurations before finalizing the specifications of the RTX 3080 Ti and may have eventually dropped the idea of the 12GB model when it found that rival AMD had released the RX 6800 series with 16 gigs of VRAM as competitors to its 10GB RTX 3080.
|RTX 3080||RTX 3080 Ti 12GB||RTX 3080 Ti 20GB||RTX 3090|
|Memory Capacity||10GB GDDR6X||12GB GDDR6X||20GB GDDR6X||24GB GDDR6X|
|Memory Clock||19 Gbps||N/A||19 Gbps||19.5 Gbps|
While we can't say for sure, it is likely that the severe ongoing graphics card shortage led to the abandoning of the 20GB RTX 3080 Ti too. There simply may not be enough chips to launch another GPU with a cut-down VRAM configuration and Nvidia may have instead opted to repurpose those (via @VideoCardz) to RTX 3090 models instead.
Source and image: hardwareLUXX