https://www.techpowerup.com/294002/nvidia-rtx-3090-ti-memory-overclocked-to-24-6-gbps-yielding-1-18-tb-s-bandwidth
 
The 21 Gbps-rated GDDR6X memory chips powering the GeForce RTX 3090 Ti really like to overclock. During our testing, we've seen these things reach as high as 1500 MHz (real clock), or 24 Gbps. Tweaktown, in the course of their crypto-mining performance testing of the RTX 3090 Ti, has managed to set a memory clock record, reaching as high as 1538 MHz, or 24.6 Gbps, which works out to a staggering 1181 GB/s memory bandwidth. 24.6 Gbps, VideoCardz notes, is higher than even the rumored 24 Gbps memory clock speed of the RTX 4090, the next-generation flagship powered by the Ada Lovelace graphics architecture. Armed with blistering memory speeds and larger on-die caches, the memory sub-system is poised to once again be a major contributor to the RTX 40-series generational performance uplift. Tweaktown set its RTX 3090 Ti memory OC feat with an MSI RTX 3090 Ti SUPRIM X graphics card.
 
That is a fantastic overclock. Next gen GPU memory should also have some great memory overclocking potential.