Zen 5 also seems to have a bit of a underperforming memory subsystem, from what I can gather.

Hardware Unboxed just did an interesting video[1] comparing gaming performance of 7600X Zen 4 and 9700X Zen 5 processors, and also the 9800X3D for reference. In some games the 9700X Zen 5 had a decent lead over the Zen 4, but in others it had exactly the same performance. But the 9800X3D would then have a massive lead over the 9700X.

For example, in Horizon Zero Dawn benchmark, the 7600X had 182 FPS while the 9700X had 185 FPS, yet the 9800X3D had a massive 266 FPS.

[1]: https://www.youtube.com/watch?v=emB-eyFwbJg

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VHRanger 3 days ago | parent [-]

I mean, huge software with a ton of quirks like a AAA video game are arguably not a good benchmark to understand hardware.

They're still good benchmarks IMO because they represent a "real workload" but to understand why the 9800X3D performs this much better you'd want some metrics on CPU cache misses in the processors tested.

It's often similar to hyperthreading -- on very efficient sofware you actually want to turn SMT off sometimes because it causes too many cache evictions as two threads fight for the same L2 cache space which is efficiently utilized.

So software having a huge speedup from a X3D model with a ton of cache might indicate the sofware has a bad data layout and needs the huge cache because it keeps doing RAM round trips. You'd presumably also see large speedups in this case from faster RAM on the same processor.

	▲	magicalhippo 3 days ago \| parent [-]
		> but to understand why the 9800X3D performs this much better you'd want some metrics on CPU cache misses in the processors tested. But as far as I can tell the 9600X and the 9800X3D are the same except for the 3D cache and a higher TDP. However they have similar peak extended power (~140W) and I don't see how the different TDP numbers explain the differences between 9600X and 7600X where the is sometimes ahead and other times identical, while the 9800X3D beats both massively regardless. What other factors could it be besides fewer L3 cache misses that lead to 40+% better performance of the 9800X3D? > You'd presumably also see large speedups in this case from faster RAM on the same processor. That was precisely my point. The Zen 5 seems to have a relatively slow memory path. If the M-series has a much better memory path, then the Zen 5 is at a serious disadvantage for memory-bound workloads. Consider local CPU-run LLMs as a prime example. The M-s crushes AMD there. I found the gaming benchmark interesting because it represented workloads that had workloads that just straddled the cache sizes, and thus showed how good the Zen 5 could be had it had a much better memory subsystem. I'm happy to be corrected though.