Latency is more important than bandwidth when it comes to reading and writing data, except for specialized work loads. I don't know the delay for current gen g

Latency is more important than bandwidth when it comes to reading and writing data, except for specialized work loads. I don't know the delay for current gen graphics cards, but when CUDA first came out in '07 vram had a roughly a 10x delay to system ram. vram would work great as virtual memory, where chunks of ram can be loaded and unloaded when the systems main memory runs out, but using vram as system ram today isn't ideal. Likewise running an ssd as system ram wouldn't be ideal either. This is one of the reasons why cache sizes have increased so much throughout the years. It's not just more cores. The cpu is branching out further pulling in data that will be hypothetically necessary in a few ms. Using vram you'd need the cpu to prefetch hundreds of ms ahead of time. This would add a lot of complexity to the cpu. AMD announced a cpu with a 256MB L3 cache. Imagine, in 10 years a cpu with 1GB of cache.