The memory problem nobody brags about.
A Mixture-of-Experts model is a crowd of specialists. Qwen3-30B-A3B has 128 experts in each layer. For every token, a little router picks 8 of them and the rest sit the turn out.
That's why it only does about 3B params of work per token even though it's 30B big. Cheap to run, in theory. The catch: all 128 experts still have to live in memory, ready, in case the router calls on them.
Watch the panel: tokens drop into the router, which lights up 8 experts at a time. Every square is full size, because every expert is stored at 16 bits.

