CPU choices and 3D productivity build - Low TDP and wattage options?

[garetjax27]

This is going to echo a post I made about GPU selection: If you're choosing a CPU for 3D modeling and scanning (no gaming), are you going Intel or AMD, and why?

And to follow-up, if you need a processor for the above that is low TDP and low wattage, would that change your decision of CPU maker? If so, how come?

Basically, I'm looking to build a SFF productivity PC that won't turn my office into an inferno and won't sound like a jet taking off - hence the low TDP and low wattage requirement. At first blush, I was thinking Ryzen 9 7900 or 7900X3D as I read that AMD is much more power efficient and delivers better results when it comes to performance vs. TDP/wattage than Intel. Regardless of CPU, I am planning to run an AIO, preferably a 240mm.

Am I off the mark? What CPU would you choose for my use case?

 

[pitingres]

AMD is better for power efficiency than current Intel generations. If you aren't gaming, I doubt that the X3D variants will benefit you; I'd stick to the non-X3D units. And, before dumping money into a multi-core CPU, I'd make sure that the specific software you run can scale with additional cores. Not all of them can, it seems.

 

[bwang]

What workflow? Interactive 3D modeling is mostly single threaded so regardless of the CPU TDP you're not pulling much more than 60W or so. 3D scanning really depends on the software.

AMD is not more efficient than Intel, AMD simply chooses a more efficient operating point. You pick the TDP - most reasonable motherboards will let you set the operating point manually. If you want good performance per watt pick the highest core count part you can afford and set a fixed TDP, the way V/f curves work more cores at a lower clock speed gets more work done per joule. Low-threaded workloads will still run well because turbo will float and give you a few cores at high frequencies.

My vote is always the 7950x for workstation applications, simply because it doesn't have E-cores. The scheduler is getting better but obscure workstation applications might wind up on the wrong cores.

 

[Keljian]

Someone I know uses a 13500 for dev work, it’s plenty fast and runs cool enough for a sff case. If you want a fire breathing pc, you can build one, but the midrange chips are plenty fast for the majority of applications

 

[pgaster]

Not an expert, but I am an engineer and have been trying to follow CAD benchmarks for a long time so this topic is kind of up my alley.
I'll try to post some things and examples I have come across.

I'm not sure why, but Intel is faster at some modeling, SolidWorks for example. A long time ago some compilers were more optimized for Intel, maybe it's still that way for certain things.
AEC magazine has some CAD benchmarks. See pages 8-9 of the January 2023 magazine. Then check out the SolidWorks rebuild scores. Intel is faster for that one. I know it's a year old, but they test a 13900k vs a 7950X, and the 14900k is basically the same as the 13900k so I think this is still relevant.
https://aecmag.com/magazines/

In terms of power, everyone talks about how Intel uses more power at load. Not many talk about about how Intel uses less power at idle.
https://www.reddit.com/r/Amd/comments/10evt0z/ryzen_vs_intels_idle_power_consumption_whole/
Of course Intel is saving 30 to 40 watts at idle, but can use way more at load, so overall AMD might be a better option. Like bwang said though, you can drop the power use in the bios with Intel. Single threaded performance will not drop much, if at all.
If you get a 7900X or 7950X those are 170 Watt cpus but there is a 105W ECO mode that can drop power a decent amount while barely changing performance.
The ECO modes do not affect single threaded performance really, just multi threaded performance, so for CAD use ECO mode would be a great idea.

Single threaded performance really is king for modeling, and the extra cache of the 7800X3D does not seem to help in many CAD situations. Also the lower clock speed lowers the single threaded performance.
https://www.igorslab.de/en/amd-ryze...ast-gaming-in-a-different-energy-dimension/8/
Just trying to point out that this particular cpu might not be the best AMD choice for CAD. Everyone loves it for gaming but CAD isn't gaming.

Overall, an Intel system might be the best choice right now, per AEC benchmarks, if you use SolidWorks, but LGA 1700 is a dead end.
We don't know what might happen on AM5. Zen 5 will come out this year and should only take a bios update for boards to be ready. If you are thinking more long term, and do not mind a cpu upgrade later, the AM5 platform might be the best bet.
Some leak sites have even speculated that Zen 6 might also be on AM5 but this is years out and I would not for sure bet on that happening. Good to know though that it may be possible.