The MoE architecture allows you to keep the entire active model on a single GPU. If two consecutive tokens use the same export then the second token is going to be much faster.
Two GPUs or more mean you can start to "keep" one or more of the experts hot on a GPU as well.
Ktransformers has a document about using CPU + a single 4090D to reach decent tokens/s but I'm not sure how much of the perf is due to the 4090D vs other optimizations/changes for the CPU side https://github.com/kvcache-ai/ktransformers/blob/main/doc/en... The final step of going to 6 experts instead of 8 feels like cheating (not a lossless optimization).
K (K=8 for these models, but you can customize that if you want) experts of 256 per layer are activated at a time. The 256 comes from the model file, it's just how many they chose to build it with. In these models there is also 1 shared expert which is always active in the layer. The router picks which k routed experts to use each forward pass and then a gating mechanism combines the outputs. If you sum the 1 shared expert + K routed experts + router + output networks you end up with 37 B parameters active for each feed forward layer pass. The individual experts are therefore much smaller than the total (probably something like 4 B parameters each? I've never really checked that directly).
Or, for the short answer: "37 B is the active parameters of 9 experts + 'overhead', not the parameters of a single expert".