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I am torn on i9-13900k vs 7900X. Anyone have linux workstation experience with one of these? Missed a big discount on the 7900 yesterday (prime day) but been le

I am torn on i9-13900k vs 7900X. Anyone have linux workstation experience with one of these? Missed a big discount on the 7900 yesterday (prime day) but been leaning towards Intel. Just wondering how Linux does with the perf vs. efficiency cores.

sounds 3y ago
Phoronix test suite should have the data.
- whalesalad 3y ago
  i9 wins in most workloads, and it supports DDR4 which is a perk since I don't particularly see a need for DDR5 and the former is a lot cheaper.
  - dhruvdh 3y ago
    You may also want to consider power and heat; I don't have numbers to share but I think 13900k is understood to be hot and power hungry.
  - raihansaputra 3y ago
    one thing i kinda regret with going with DDR4 13-gen: the ability to have 48GB per DIMM slot instead of getting maxed out at 32GB per slot. I'm on a mini-ITX system with 2 DIMM slots.
pm2222 3y ago
7945hx I like
- tiffanyh 3y ago
  The GP is asking about desktop cpu's, the 7945hx is a laptop cpu.
  - pm2222 3y ago
    7945hx is very powerful and worth looking into based on cpubenchmark. Frankly I don’t know much about avx512 performance though.
jeffbee 3y ago
The 13900K has more cores and depending on your use case that might be nice. As a software developer, I find the "efficiency cores" of the 13900K to be similar in steady-state throughput to the "performance cores" for embarrassingly parallel workloads like C++ builds or ETL from JSON. An analogy I have made before is the e-cores are like having a Xeon Gold 6130 as a coprocessor. If your use-case is different than mine, you might have a different experience. I also find it amusing, although not professionally relevant, to experiment with the unusual abilities of the 13900K that descend from its Atom lineage: clusters of 4 e-cores that share L2, and the WAITPKG ISA extension that makes switching threads extremely fast. On the other hand the 7900X has AVX-512 and I would rather have that instead.
- whalesalad 3y ago
  I will need to do some digging on AVX-512. This is my current dev box, which is pretty old by todays standards. https://i.imgur.com/ebwJlBi.png https://i.imgur.com/ebwJlBi.png
  - jeffbee 3y ago
    Coming off that machine, I guess I would consider a Xeon w7-3455 even though it costs a lot more. Definitely more comparable to that league of machine.
    - whalesalad 3y ago
      mama mia https://www.cdw.com/product/lenovo-thinkstation-p7-tower-xeon-w7-3455-2.5-ghz-vpro-enterprise-1/7437167 https://www.cdw.com/product/lenovo-thinkstation-p7-tower-xeo...
- rlupi 3y ago
  I haven't touched a 7900X, but AMD Rome and Milan have core complex (CCX) that share 16MB L3 cache. AMD Rome has significantly faster L3 cache than Intel (https://www.anandtech.com/show/14694/amd-rome-epyc-2nd-gen/7 https://www.anandtech.com/show/14694/amd-rome-epyc-2nd-gen/7) and generally more of it overall, but it is split among many CCX. This fragmentation can be a problem. --- On the 13900K... At home, I have a 13900K (128G 4090 8T+8TSSD) and use Mathematica often for personal use. I installed it intially in Windows 11 Pro and got abysmal performance in benchmarks (worse than 12900 equivalent processor). With help from Wolfram customer support, I switched to Linux (Ubuntu): the performance is on par with what I'd expect. My hypothesis is that either the Windows scheduler for Windows 11 Pro optimizes for a different performance point than Linux, or that it was oblivious of performance vs. efficiency core (13900K has double the efficiency cores of the previous generation, so if you pick randomly you have a lot more chances to end up in a slow core). This was in the previous minor release of Mathematica, I hope they implemented a workaround in the latest version. I don't think it was a Mathematica bug, but an OS-level problem (I haven't tried, but I can it would be easy to check): many report that stable diffusion works better on Linux than Windows. My personal toy project was a reinforcement learning thing, for which the CPU was the bottleneck on Windows (performance on par with MacStudio M1 Max) and I saw nearly 2x improvement switching to Linux.

sounds 3y ago

Phoronix test suite should have the data.

whalesalad 3y ago
i9 wins in most workloads, and it supports DDR4 which is a perk since I don't particularly see a need for DDR5 and the former is a lot cheaper.
- dhruvdh 3y ago
  You may also want to consider power and heat; I don't have numbers to share but I think 13900k is understood to be hot and power hungry.
- raihansaputra 3y ago
  one thing i kinda regret with going with DDR4 13-gen: the ability to have 48GB per DIMM slot instead of getting maxed out at 32GB per slot. I'm on a mini-ITX system with 2 DIMM slots.

pm2222 3y ago

7945hx I like

tiffanyh 3y ago
The GP is asking about desktop cpu's, the 7945hx is a laptop cpu.
- pm2222 3y ago
  7945hx is very powerful and worth looking into based on cpubenchmark. Frankly I don’t know much about avx512 performance though.

jeffbee 3y ago

The 13900K has more cores and depending on your use case that might be nice. As a software developer, I find the "efficiency cores" of the 13900K to be similar in steady-state throughput to the "performance cores" for embarrassingly parallel workloads like C++ builds or ETL from JSON. An analogy I have made before is the e-cores are like having a Xeon Gold 6130 as a coprocessor. If your use-case is different than mine, you might have a different experience. I also find it amusing, although not professionally relevant, to experiment with the unusual abilities of the 13900K that descend from its Atom lineage: clusters of 4 e-cores that share L2, and the WAITPKG ISA extension that makes switching threads extremely fast. On the other hand the 7900X has AVX-512 and I would rather have that instead.

whalesalad 3y ago
I will need to do some digging on AVX-512. This is my current dev box, which is pretty old by todays standards. https://i.imgur.com/ebwJlBi.png https://i.imgur.com/ebwJlBi.png
- jeffbee 3y ago
  Coming off that machine, I guess I would consider a Xeon w7-3455 even though it costs a lot more. Definitely more comparable to that league of machine.
  - whalesalad 3y ago
    mama mia https://www.cdw.com/product/lenovo-thinkstation-p7-tower-xeon-w7-3455-2.5-ghz-vpro-enterprise-1/7437167 https://www.cdw.com/product/lenovo-thinkstation-p7-tower-xeo...
rlupi 3y ago
I haven't touched a 7900X, but AMD Rome and Milan have core complex (CCX) that share 16MB L3 cache. AMD Rome has significantly faster L3 cache than Intel (https://www.anandtech.com/show/14694/amd-rome-epyc-2nd-gen/7 https://www.anandtech.com/show/14694/amd-rome-epyc-2nd-gen/7) and generally more of it overall, but it is split among many CCX. This fragmentation can be a problem. --- On the 13900K... At home, I have a 13900K (128G 4090 8T+8TSSD) and use Mathematica often for personal use. I installed it intially in Windows 11 Pro and got abysmal performance in benchmarks (worse than 12900 equivalent processor). With help from Wolfram customer support, I switched to Linux (Ubuntu): the performance is on par with what I'd expect. My hypothesis is that either the Windows scheduler for Windows 11 Pro optimizes for a different performance point than Linux, or that it was oblivious of performance vs. efficiency core (13900K has double the efficiency cores of the previous generation, so if you pick randomly you have a lot more chances to end up in a slow core). This was in the previous minor release of Mathematica, I hope they implemented a workaround in the latest version. I don't think it was a Mathematica bug, but an OS-level problem (I haven't tried, but I can it would be easy to check): many report that stable diffusion works better on Linux than Windows. My personal toy project was a reinforcement learning thing, for which the CPU was the bottleneck on Windows (performance on par with MacStudio M1 Max) and I saw nearly 2x improvement switching to Linux.