Unlike DDR, GDDR is optimised for high-bandwidth (over latency), which is why dedicated GPUs can be so much faster. HBM even more so. DDR5 does 6.4Gbps, whereas

Unlike DDR, GDDR is optimised for high-bandwidth (over latency), which is why dedicated GPUs can be so much faster. HBM even more so. DDR5 does 6.4Gbps, whereas HBM2E does 2.5Tbps (per stack).