I can totally see why people are so frustrated by this post. Dude buys an 8 core and runs it at a quarter performance for the sake of power savings. You might as well buy a 6-core and run it normally. It'll give you more per-core performance which is usually more efficient than multithreading. You'll save more energy cuz ur not powering two extra cores to begin with. You'll save money on buying the actual CPU.
The only use case where this MIGHT make sense is if he only puts it in regular power mode for intense tasks, and low power otherwise. But OP is making a point about his undervolted benchmarks under high load, which is irrelevant to that specific use case. And the power/heat savings at idle or low load is almost negligible because heat is only significantly generated during heavy load. You can understand OP's point and intended use case, but the conclusion doesn't correlate to his benchmarks and it doesn't make much practical difference in terms of power savings.
The 3900X is a 12 C 24T.
I've noticed the sweet spot to be about 15% lower in both clockspeed and vCore on any Ryzen CPU (except maybe the R5 1600AF). To me that simply means AMD has overclocked the chips out the door. Same with their GPU's, obscenely overclocked as stock.Calavaro, do you by any chance able to map out performance versus power consumption to create a power efficiency curve and see if there is any inflection point (sweet spot) on whatever tasks that you can run for some time and benchmark it? I did a study on GPU here back in 2016. I'm not sure how you want to define "performance" in your case but in distributed computing perspective we call this PPD (points per day). I do run my rigs 24/7, hence power efficiency is really important to me. Other than the server chips which is designed for performance and efficiency, I'm interested in consumer chips for my next possible upgrade. The 16 core ryzen is tempting.
BTW, I've running old xeon chips (from sandy bridge to haswell). The big epyc server motherboard is quite expensive, hence I'm interested to know this, if it is available.
These chips can run really well at very low power especially if multi threading isn't a necessity for your application. Here are the results of my testing without SMT on a 3800.
Tried it but the additional power requirement caused hitching while gaming and it was very annoying. Maybe it was clock stretching. Never bothered to investigate. Don't be fooled by my username I've been ocing amd cpus since the thunderbird procs were new.
I think I see what your getting at but with AMD doesn’t speed = more cores as far as their binning process goes? So if you want to get an AMD part for gaming and you end up getting the fastest you also have the most cores even if the cores aren’t for your particular uses?Bit of topic. But some of my friends drive "performance" cars. You know, like Porche's and such. I tell them I too drive a performance car, it's a Honda Civic Hybrid.
I think I see what your getting at but with AMD doesn’t speed = more cores as far as their binning process goes? So if you want to get an AMD part for gaming and you end up getting the fastest you also have the most cores even if the cores aren’t for your particular uses?