[mikrl]

From the newegg listing:

>8 Cores and 16 processing threads, based on AMD "Zen 5" architecture

which is the same thread geometry as my 9900K.

My main concerns at the time were:

1. More cores for running large workloads on k8s since I had just upgraded to 128G RAM

2. More thread level parallelism for my C++ code

Naively I thought that, ceteris paribus and assuming good L1 cache utilization, having more physical cores with a higher clock rate would be the ticket for 2.

Does the 9800X3D have a wider pipeline or is it some other microarchitectural feature that makes it faster?

[Aurornis]

Comparing CPUs by clock speed doesn’t work. New CPUs are do more work per clock cycle.

A 9800X3D is twice as fast as your 9900K in benchmarks like GeekBench, despite having similar clock speed and the same core count.

If you could downclock the AMD part to 2.5GHz as an experiment it would still beat your 5GHz 9900K.

[joefourier]

You don't even need to go into the pipeline details. The 9800X3D has 8x more L2 cache, 6x more L3 cache, 2x the memory bandwidth than the now 8 years old i9 9900K. 3D V-cache is pretty cool.

[kllrnohj]

I purposely picked a CPU with the same thread geometry as your 9900K to avoid calls of "apples & oranges" or whatever. If you want more threads, the 9950X is right there in the same socket. Or Core Ultra 9 285k. Either of which will run circles around a 9900K in code compilation.

You can research microarchitecture differences if you want, it's a fascinating world, or you can just skip to looking at benchmarks/reviews. Little hard to compare against quite that large of a generation gap, but eg https://gamersnexus.net/cpus/rip-intel-amd-ryzen-7-9800x3d-c... or https://www.phoronix.com/review/amd-ryzen-7-9800x3d-linux/2

[zzzoom]

The 9800X3D has wider everything. Decoder, execution ports, vectors, cache, memory bandwidth...

[mikrl]

I think my i9 was released right after the Spectre and Meltdown mitigations in 2019, but I seem to remember even more recent vulns in that family… so that could also be a factor.