PCIe 3.0 x16 is a 16 GB/s link, which ain’t bad. By comparison, CPU dual channel DDR4-2400 main memory is 38.4 GB/s. All processors are memory bandwidth starv

PCIe 3.0 x16 is a 16 GB/s link, which ain’t bad. By comparison, CPU dual channel DDR4-2400 main memory is 38.4 GB/s. All processors are memory bandwidth starved. CPUs don’t benefit from wide, high latency access to large main memory as much as GPUs, due to the nature of SISD vs. SIMD. Naturally, GPUs put more focus on a fatter pipe between the processor and main memory (GDDR and 500 GB/s pipes). CPUs operate on fewer data, so you can crank the speed of computation up if you crank the memory speed and keep latency low. This is why so much of CPU dies are dedicated to cache (I think L1 is often single cycle, which results in absurd throughout numbers).