LLM speed is roughly <memory_bandwidth> / <model_size> tok/s.
DDR4 tops out about 27Gbs
DDR5 can do around 40Gbs
So for 70B model at 8 bit quant, you will get around 0.3-0.5 tokens per second using RAM alone.
DDR4 tops out about 27Gbs
DDR5 can do around 40Gbs
So for 70B model at 8 bit quant, you will get around 0.3-0.5 tokens per second using RAM alone.
In general systems usually have PCIE version with bandwidth better than RAM of that system.
For example a system with DDR4 (27Gbs) usually has at least PCIE4 (32Gbs at 16x).
But you can bottleneck that by building a DDR5 (40Gbs) system with PCIE4 card.
LLama 3.1 however is not MoE, so all params are active.
For MoE it is tricky, because for each token you only use a subset of params (an “expert”) but you don’t know which one, so you have to keep them all in memory or wait until it loads from slower storage, potentially different for each token.