Micron in the briefing listed the RTX 3090 in a chart as having 12 GDDR6X modules, 19-21 Gb/s/pin, 76-84 GB/s/placement, 912-1008 GB/s/system and a total frame buffer of 12 GB.
https://www.techspot.com/news/86385-micron-slips-up-reveals-details-nvidia-upcoming-rtx.html?utm_source=dlvr.it&utm_medium=blogger
https://www.techspot.com/news/86385-micron-slips-up-reveals-details-nvidia-upcoming-rtx.html?utm_source=dlvr.it&utm_medium=blogger