Extra Cache

[Werewolf]

Any ideas if this will help for chess? In the past extra cache didn't seem to do much, but that was before NNUE and I'm wondering if anything has changed.

It seems to be almost double the cache on the new AMD CPUs with a very small reduction in clock speed.

https://www.tomshardware.com/news/amd-u ... x-cpus-too

[smatovic]

According to

https://openbenchmarking.org/test/pts/stockfish

with Stockfish 15:

AMD Ryzen 7 5800X3D 8-Core 29367288 NPS
AMD Ryzen 7 5800X 8-Core 29046122 NPS

the 5800X3D has 96 MB the 5800X 32 MB L3 cache.

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Srdja

[Werewolf]

According to

https://openbenchmarking.org/test/pts/stockfish

with Stockfish 15:

AMD Ryzen 7 5800X3D 8-Core 29367288 NPS
AMD Ryzen 7 5800X 8-Core 29046122 NPS

the 5800X3D has 96 MB the 5800X 32 MB L3 cache.

--
Srdja

Thanks for the info.
Shame it's only a 1% difference.

Interestingly on that list the 7773X (single CPU, Milan generation) with 3D cache is quite a bit better than any other 64 core processor without it.

[Ras]

the 5800X3D has 96 MB the 5800X 32 MB L3 cache.

But also lower clocks because the extra layer of silicon acts as a thermal insulator: base clock 3.4 vs 3.8GHz, max boost 4.5 vs. 4.7GHz. The extra cache is really about reducing latency because that's what benefits games, but not so much applications. Similarly for the new 7000X3D.

Also with the new 7000X3D chips, the variants with two chiplets (12 and 16 cores) have that extra cache only on one of them. For games to actually profit from that, they would have to be scheduled accordingly. Microsoft won't add that to Windows 10 two years before EOL now, and I doubt that AMD has working together with Microsoft early enough to have Windows 11 support for that out of the box.

[Werewolf]

the 5800X3D has 96 MB the 5800X 32 MB L3 cache.

But also lower clocks because the extra layer of silicon acts as a thermal insulator: base clock 3.4 vs 3.8GHz, max boost 4.5 vs. 4.7GHz. The extra cache is really about reducing latency because that's what benefits games, but not so much applications. Similarly for the new 7000X3D.

Also with the new 7000X3D chips, the variants with two chiplets (12 and 16 cores) have that extra cache only on one of them. For games to actually profit from that, they would have to be scheduled accordingly. Microsoft won't add that to Windows 10 two years before EOL now, and I doubt that AMD has working together with Microsoft early enough to have Windows 11 support for that out of the box.

Interesting, that makes sense.

I suppose my question would be why is it then that the top performing CPUs (both single and dual sockets) have the 3D cache?

[Ras]

I suppose my question would be why is it then that the top performing CPUs (both single and dual sockets) have the 3D cache?

At least in desktop, that's not the case outside of games. The 5800X is faster in applications than the 5800X3D, and that's because throughput matters more than latency. For the 7000X3D, we don't have independent application benchmarks yet.

E.g. Cinebench R23 single/multi: 5800X 1602/15372, 5800X3D 1540/13372 (source: https://youtu.be/TqWdG4qj8ww?t=18). Even in single where the thermal 3D issue isn't as pronounced, the X3D is slower, and a lot more so in multi.

Consider also price to performance in applications. The 5800X is 236 EUR, the 5800X3D 365 EUR. So in the metrics of "CB23 multi points per EUR", the 5800X scores 65.1. However, the 5800X3D only manages 36.6, which is a lousy value proposition for applications.