Question: is gddr5 compatible with gddr6?
Answer: As long as the motherboard in question has a PCIe slot, (preferably one running in PCIe 3.0 x16 mode to get the most out of your graphics card) then you can run any modern graphics card no problem, regardless of the type of VRAM. Most modern graphics cards will either use GDDR5, GDDR5X, GDDR6, or HBM2.