Global shortage of GDDR6 is a dominant factor in the supply shortages being faced by AMD Radeon RX 5000, RX 6000, NVIDIA RTX 3070, and RTX 3060 Ti GPUs with the situation likely to improve only around February 2021. The RTX 3080 and RTX 3090 cards with GDDR6X memory are somewhat less-impacted, but limited production from Samsung Foundry means that their availability is questionable at least till end of Q3 2020.
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