20200418, 00:37  #12 
Jan 2019
Pittsburgh, PA
3·7·11 Posts 
I finally put together my 3950x, this is what I'm seeing, not exactly impressive maybe I'm missing something.
Specs: Asrock matx x570, 3950x, 4x16gb ddr43466 171919 It's really weird this processor seldom jumps 10 degrees then goes back down, and jumps again. Temperature fluctuates a lot. This shouldn't happen, at least I didn't expect it to. Hope this helps anyone who's planning to buy one. Let me know if you want me to run any specific tests. 
20200418, 05:16  #13 
"Kieren"
Jul 2011
In My Own Galaxy!
97·103 Posts 
What is the CPU cooling? I'm wondering about thermal interface issues.
Is this 4 channel memory? If so, I am in awe of such a system. EDIT: Well I am in awe, regardless. Last fiddled with by kladner on 20200418 at 05:18 
20200418, 06:25  #14  
Jan 2019
Pittsburgh, PA
E7_{16} Posts 
Quote:
According to data given by others i.e. The Judger on the 3900x, it seems like 3950x is not a good choice economically speaking, at least for use in Prime95. Compared to his data on FFT around DC range I think 2880K, I'm only getting a max of 790iter/ms (12 cores) compared to his 850iter/ms on the 3900x. Cooler is the corsair h115i pro. Not sure why the temperature randomly spikes every 30 seconds or so, maybe its a ryzen thing, but guess will try to reapply thermal paste and see what happens. Take care, everyone. 

20200418, 06:56  #15 
Romulan Interpreter
Jun 2011
Thailand
2·11·397 Posts 
Re: the new title of thread, ("is the 3900x overkill?")  there is not overkill in distributed computing world. If you can afford the money for hardware and electricity, then the more hardware the merrier...

20200418, 12:16  #16  
"Composite as Heck"
Oct 2017
2·313 Posts 
Quote:
Zen2 (and probably all CPUs going forwards) act more like a GPU by automatically boosting when thermal limits allow. Under steady load I wouldn't expect a lot of temperature jumps, maybe the load isn't steady as a result of the disjoint L3 causing some unpredictable access times or maybe 10 degrees just isn't that big a jump. If you're in a testing mood you could try optimising for a 50M exponent with single channel memory, this would simulate quarter of a 3990X and answer part of this question ( https://www.mersenneforum.org/showthread.php?t=25463 ). The question also includes 90M and 332M exponents but unless you're particularly bored I wouldn't bother as GPUs are much better suited to large exponents. 

20200418, 15:37  #17  
Jul 2018
Martin, Slovakia
2×3^{2}×7 Posts 
Quote:
EDIT: I forgot to mention now I have it on 4,1 GHz overclock on all cores, and when I turn on Prime95, I set fans to 100%, and no fluctuations whatsoever under load. I should also mention that spiking occurred only when not under load on stock settings. Last fiddled with by Viliam Furik on 20200418 at 15:40 

20200419, 00:27  #18  
Jan 2019
Pittsburgh, PA
11100111_{2} Posts 
Quote:
Here's some data on different FFTs, I switched to 3333mhz cas15 memory this time. Code:
Prime95 64bit version 29.8, RdtscTiming=1 Timings for 2560K FFT length (12 cores, 1 worker): 1.19 ms. Throughput: 840.80 iter/sec. Timings for 2560K FFT length (12 cores hyperthreaded, 1 worker): 1.14 ms. Throughput: 879.66 iter/sec. Timings for 2688K FFT length (12 cores, 1 worker): 1.19 ms. Throughput: 838.49 iter/sec. Timings for 2688K FFT length (12 cores hyperthreaded, 1 worker): 1.26 ms. Throughput: 795.96 iter/sec. Timings for 2800K FFT length (12 cores, 1 worker): 1.41 ms. Throughput: 708.21 iter/sec. Timings for 2800K FFT length (12 cores hyperthreaded, 1 worker): 1.52 ms. Throughput: 658.88 iter/sec. Timings for 2880K FFT length (12 cores, 1 worker): 1.36 ms. Throughput: 734.25 iter/sec. Timings for 2880K FFT length (12 cores hyperthreaded, 1 worker): 1.47 ms. Throughput: 678.32 iter/sec. Timings for 3072K FFT length (12 cores, 1 worker): 1.42 ms. Throughput: 703.88 iter/sec. Timings for 3072K FFT length (12 cores hyperthreaded, 1 worker): 1.42 ms. Throughput: 705.53 iter/sec. Timings for 3200K FFT length (12 cores, 1 worker): 1.47 ms. Throughput: 678.45 iter/sec. Timings for 3200K FFT length (12 cores hyperthreaded, 1 worker): 1.45 ms. Throughput: 690.52 iter/sec. Timings for 3360K FFT length (12 cores, 1 worker): 1.51 ms. Throughput: 664.09 iter/sec. Timings for 3360K FFT length (12 cores hyperthreaded, 1 worker): 1.46 ms. Throughput: 684.63 iter/sec. Timings for 3584K FFT length (12 cores, 1 worker): 1.63 ms. Throughput: 614.33 iter/sec. Timings for 3584K FFT length (12 cores hyperthreaded, 1 worker): 1.56 ms. Throughput: 641.42 iter/sec. Timings for 3840K FFT length (12 cores, 1 worker): 1.74 ms. Throughput: 575.05 iter/sec. Timings for 3840K FFT length (12 cores hyperthreaded, 1 worker): 1.70 ms. Throughput: 588.05 iter/sec. Timings for 4096K FFT length (12 cores, 1 worker): 1.84 ms. Throughput: 543.58 iter/sec. Timings for 4096K FFT length (12 cores hyperthreaded, 1 worker): 1.76 ms. Throughput: 567.93 iter/sec. Timings for 4480K FFT length (12 cores, 1 worker): 2.08 ms. Throughput: 481.58 iter/sec. Timings for 4480K FFT length (12 cores hyperthreaded, 1 worker): 2.05 ms. Throughput: 487.49 iter/sec. Timings for 4608K FFT length (12 cores, 1 worker): 2.09 ms. Throughput: 478.69 iter/sec. Timings for 4608K FFT length (12 cores hyperthreaded, 1 worker): 2.13 ms. Throughput: 468.51 iter/sec. Timings for 4800K FFT length (12 cores, 1 worker): 2.16 ms. Throughput: 462.00 iter/sec. Timings for 4800K FFT length (12 cores hyperthreaded, 1 worker): 2.08 ms. Throughput: 479.87 iter/sec. Timings for 5120K FFT length (12 cores, 1 worker): 2.34 ms. Throughput: 428.14 iter/sec. [Sat Apr 18 19:22:58 2020] Timings for 5120K FFT length (12 cores hyperthreaded, 1 worker): 2.32 ms. Throughput: 431.55 iter/sec. Timings for 5376K FFT length (12 cores, 1 worker): 2.68 ms. Throughput: 373.61 iter/sec. Timings for 5376K FFT length (12 cores hyperthreaded, 1 worker): 2.84 ms. Throughput: 352.25 iter/sec. Timings for 5600K FFT length (12 cores, 1 worker): 2.85 ms. Throughput: 351.09 iter/sec. Timings for 5600K FFT length (12 cores hyperthreaded, 1 worker): 2.98 ms. Throughput: 335.68 iter/sec. Timings for 5760K FFT length (12 cores, 1 worker): 3.16 ms. Throughput: 316.13 iter/sec. Timings for 5760K FFT length (12 cores hyperthreaded, 1 worker): 3.71 ms. Throughput: 269.34 iter/sec. Timings for 6144K FFT length (12 cores, 1 worker): 3.45 ms. Throughput: 290.23 iter/sec. Timings for 6144K FFT length (12 cores hyperthreaded, 1 worker): 3.57 ms. Throughput: 280.42 iter/sec. Code:
Prime95 64bit version 29.8, RdtscTiming=1 Timings for 2560K FFT length (12 cores, 2 workers): 1.95, 1.91 ms. Throughput: 1034.34 iter/sec. Timings for 2560K FFT length (12 cores hyperthreaded, 2 workers): 1.83, 1.82 ms. Throughput: 1096.38 iter/sec. Timings for 2560K FFT length (14 cores, 2 workers): 1.86, 1.84 ms. Throughput: 1080.83 iter/sec. Timings for 2560K FFT length (14 cores hyperthreaded, 2 workers): 1.65, 1.63 ms. Throughput: 1216.80 iter/sec. Timings for 2560K FFT length (16 cores, 2 workers): 1.70, 1.71 ms. Throughput: 1173.84 iter/sec. Timings for 2560K FFT length (16 cores hyperthreaded, 2 workers): 1.63, 1.63 ms. Throughput: 1227.80 iter/sec. Timings for 2688K FFT length (12 cores, 2 workers): 2.08, 2.04 ms. Throughput: 971.74 iter/sec. Timings for 2688K FFT length (12 cores hyperthreaded, 2 workers): 2.02, 2.00 ms. Throughput: 995.81 iter/sec. Timings for 2688K FFT length (14 cores, 2 workers): 1.91, 1.94 ms. Throughput: 1037.88 iter/sec. Timings for 2688K FFT length (14 cores hyperthreaded, 2 workers): 1.73, 1.73 ms. Throughput: 1155.66 iter/sec. Timings for 2688K FFT length (16 cores, 2 workers): 1.78, 1.79 ms. Throughput: 1119.54 iter/sec. Timings for 2688K FFT length (16 cores hyperthreaded, 2 workers): 1.74, 1.73 ms. Throughput: 1154.92 iter/sec. Timings for 2800K FFT length (12 cores, 2 workers): 2.23, 2.24 ms. Throughput: 895.77 iter/sec. Timings for 2800K FFT length (12 cores hyperthreaded, 2 workers): 2.22, 2.17 ms. Throughput: 910.38 iter/sec. Timings for 2800K FFT length (14 cores, 2 workers): 2.07, 2.20 ms. Throughput: 938.82 iter/sec. Timings for 2800K FFT length (14 cores hyperthreaded, 2 workers): 1.95, 1.93 ms. Throughput: 1031.45 iter/sec. Timings for 2800K FFT length (16 cores, 2 workers): 2.22, 2.22 ms. Throughput: 900.80 iter/sec. Timings for 2800K FFT length (16 cores hyperthreaded, 2 workers): 1.93, 1.93 ms. Throughput: 1037.16 iter/sec. Timings for 2880K FFT length (12 cores, 2 workers): 2.30, 2.29 ms. Throughput: 870.46 iter/sec. Timings for 2880K FFT length (12 cores hyperthreaded, 2 workers): 2.37, 2.31 ms. Throughput: 855.47 iter/sec. Timings for 2880K FFT length (14 cores, 2 workers): 2.02, 2.18 ms. Throughput: 954.38 iter/sec. Timings for 2880K FFT length (14 cores hyperthreaded, 2 workers): 1.92, 1.91 ms. Throughput: 1044.36 iter/sec. Timings for 2880K FFT length (16 cores, 2 workers): 1.92, 2.02 ms. Throughput: 1017.67 iter/sec. Timings for 2880K FFT length (16 cores hyperthreaded, 2 workers): 1.86, 1.84 ms. Throughput: 1082.63 iter/sec. Last fiddled with by dcheuk on 20200419 at 00:38 

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