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Many GB5 (and real world) tasks are memory bandwidth bottlenecked, which greatly favors M1 Max because it has over double a Threadripper's memory bandwidth.

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Sort of. The CPU complex of the M1 Max can achieve ~200 GB/s, you can only hit the 400 GB/s mark by getting the GPU involved.

At the same time the Threadrippers also have a gargantuan amount of cache that can be accessed at several hundred gigabytes per second per core. Obviously not as nice as being able to hit DRAM at that speed.

That cache is not uniform time access. It costs over 100ns to cross the IO die to access another die's L3, almost as much as going to main memory. In practice you have to treat it as 8 separate 32 MB L3 caches.

Also, not everything fits into cache.

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