I think you misunderstand. I absolutely understand your point. I'm explicitly rejecting your point. There's a crucial difference.
The evidence laid out in this test does not necessarily lead to the conclusion you have here. There are a number of confounding factors, that if I had more time... I'd like to investigate.
True, your point is ONE possible story for what is going on here. But alas, my instincts suggest something else is going on. I think CNNs have simply been extremely well optimized for the GPU platform, and that indeed, they are one of the few algorithms that run extremely well on a GPU.
I'm curious how a well-put together "classical" chess AI would work if it were ported to a GPU. I understand that no such chess AI has ever been written, but that doesn't change my curiosity.
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EDIT:
> Chess is not strictly about computing power, and neural-network evaluation functions are vastly better.
I just thought of a way that would test this assertion. Instead of porting Stockfish to a GPU, port LeelaZero to a CPU. Run the Neural Net on the same set of hardware, and see who wins.
That way, Stockfish keeps its (cannot be scaled) centralized hash table / lazy SMP algorithm, while LeelaZero runs at the same compute-power that Stockfish has.
You can also do the reverse, it's easy to naively make Stockfish run on a GPU, it will just be performing terribly bad since it's algos will not utilize the GPU properly.
Either Stockfish's style of algorithm needs to be ported to a GPU (and I'm arguing its possible to do so efficiently. But a number of unsolved problems do have to be solved).
Or... Leela Zero needs to be ported to a CPU.
I'm not saying a naive port: I mean a port where the programmer spends a good bit of effort optimizing the implementation. That way its fair. Those are the two hypotheticals that can happen for a "fair" test.
I'm, personally, more interested in the case of Stockfish -> somehow ported to GPU, mostly because its never been done before. I mean, I don't want to do it, but if anyone ever did it, I'd be very interested in reading how they solved all of the issues. :-)
Today's Stockfish running on a low end computer would still beat Stockfish from many years ago running on a much more powerful one, because it's evaluation function is significantly better.
Chess is not strictly about computing power, and neural-network evaluation functions are vastly better.