Register FAQ Search Today's Posts Mark Forums Read

2017-04-13, 04:07   #749

"Kieren"
Jul 2011
In My Own Galaxy!

2×3×1,693 Posts

Quote:
 Originally Posted by James Heinrich According to Intel, Processor Base Frequency is 4.0GHz, Max Turbo Frequency is 4.2GHz. I would guess that Prime95 reads the processor frequency on startup before starting the actual benchmark, and turbo doesn't kick in until the CPU is under load. You could use your favourite monitoring utility (e.g. CPU-Z) to monitor CPU frequency in realtime and see how it changes as you start/run the benchmark.
The first is of course true. I have mine set to sync all cores at multiplier 42x. It still will clock down with no extra-system loading, but the clock rate is very twitchy, and goes full on with minimal load increase.

I will have to see when it goes to max when starting the benchmark. This will include trying to limit other loads (like shutting down multi-tabbed Firefox,) and maybe even mfaktc to limit whatever memory contention might arise. Of course, too, limiting other loads is not a Real Life® situation, either. Most of the time I expect this machine to do a bunch of other stuff when I want it to, and this certainly takes a toll on the ms/it.

Last fiddled with by kladner on 2017-04-13 at 04:10

 2017-04-13, 05:15 #750 db597     Jan 2003 7×29 Posts So from the benchmarks it looks like 8 Ryzen cores is still slower than 4 Skylake/Kabylake cores: Ryzen @ 3.3GHz: Code: Timings for 4096K FFT length (8 cpus, 1 worker): 6.92 ms. Throughput: 144.58 iter/sec. i7-6700K @ 4.2GHz: Code: Timings for 4096K FFT length (4 cpus, 1 worker): 4.07 ms. Throughput: 245.91 iter/sec. Given it's a new architecture, I wonder if there is AMD specific optimisation that can be done. Going above 4 cores on Ryzen yields very small gains. It could be the slow communication between the CCX. If we can keep each worker within it's own CCX, perhaps running 4 cores x 2 workers might be the most optimum for Ryzen.
 2017-04-13, 05:29 #751 Mark Rose     "/X\(‘-‘)/X\" Jan 2013 29×101 Posts The @ 4.0GHz is part of the model name when queried from the processor. It has nothing to do with the actual running processor frequency. It has confused me in the past as well. Kieren, are you running 12 GB of RAM? Kind of an odd amount. Not having matched sticks is probably hampering performance. That being said, you're getting 32% more throughput with a 27% higher CPU clock and a 50% higher memory clock compared to my systems (for 4 cores, 1 worker, 4096K FFT). That extra memory bandwidth is helping. Your benchmark also tells me I'm still memory constrained at 2133 with 4 cores at 3.3 GHz. I may try poking around the bios to see if there's a way to under a locked CPU besides disabling turbo.
2017-04-13, 12:00   #752

"Kieren"
Jul 2011
In My Own Galaxy!

236568 Posts

Quote:
 Originally Posted by Mark Rose The @ 4.0GHz is part of the model name when queried from the processor. It has nothing to do with the actual running processor frequency. It has confused me in the past as well. Kieren, are you running 12 GB of RAM? Kind of an odd amount. Not having matched sticks is probably hampering performance. That being said, you're getting 32% more throughput with a 27% higher CPU clock and a 50% higher memory clock compared to my systems (for 4 cores, 1 worker, 4096K FFT). That extra memory bandwidth is helping. Your benchmark also tells me I'm still memory constrained at 2133 with 4 cores at 3.3 GHz. I may try poking around the bios to see if there's a way to under a locked CPU besides disabling turbo.
Does it indicate 12 GB somewhere? It should be 16GB, dual channel, dual rank. They are rated at 2666MHz, running at 3200.
Attached Thumbnails

2017-04-13, 13:23   #753
VictordeHolland

"Victor de Hollander"
Aug 2011
the Netherlands

23·3·72 Posts

Quote:
 Originally Posted by db597 So from the benchmarks it looks like 8 Ryzen cores is still slower than 4 Skylake/Kabylake cores: Ryzen @ 3.3GHz: Code: Timings for 4096K FFT length (8 cpus, 1 worker): 6.92 ms. Throughput: 144.58 iter/sec. i7-6700K @ 4.2GHz: Code: Timings for 4096K FFT length (4 cpus, 1 worker): 4.07 ms. Throughput: 245.91 iter/sec.
Ryzen is about as fast as my 5?6? year old SandyBridge

i5-2500k @4.0GHz DDR3-2133
Code:
Best time for 4096K FFT length: 6.839 ms., avg: 7.155 ms.
Timings for 4096K FFT length (4 cpus, 4 workers): 27.12, 26.85, 27.58, 27.00 ms.  Throughput: 147.41 iter/sec.

2017-04-13, 15:36   #754
Mark Rose

"/X\(‘-‘)/X\"
Jan 2013

29·101 Posts

Quote:
 Originally Posted by kladner Does it indicate 12 GB somewhere? It should be 16GB, dual channel, dual rank. They are rated at 2666MHz, running at 3200.
Yeah, it does:

Code:
 Machine#0 (total=12649168KB, Backend=Windows, hwlocVersion=1.11.6, ProcessName=prime95.exe)
I doubt it will affect Prime95 though, now that you've confirmed the install RAM.

2017-04-13, 18:08   #755
James Heinrich

"James Heinrich"
May 2004
ex-Northern Ontario

3,319 Posts

Quote:
 Originally Posted by Mark Rose The @ 4.0GHz is part of the model name when queried from the processor. It has nothing to do with the actual running processor frequency.
I don't think it's the "@ 4.00 GHz" that was concerning, it was the "CPU speed: 4008.14 MHz".

Quote:
 Originally Posted by Mark Rose are you running 12 GB of RAM? Kind of an odd amount. Not having matched sticks is probably hampering performance.
That depends on the system configuration. My i7-920 system has 12GB, but it's triple-channel so 12GB is a balanced configuration. Granted most systems are dual-channel (I'm odd and my two systems are 3-channel [i7-920] and 4-channel [i7-3930K] )

As for the RAM reported, I believe that's what's available to Prime95, not total system RAM. In my case I have 64GB installed and it logs as
Code:
Machine#0 (total=54609356KB)
which is 52GB. Although I'm not entirely sure how it pulled up that number, since I have 5 workers, specified at 11000MB each, maximum 4 high-memory workers, and an overall maximum of 44000MB. But in any case, it's clearly not the installed system RAM amount.

2017-04-13, 21:08   #756

"Kieren"
Jul 2011
In My Own Galaxy!

236568 Posts

Quote:
 I don't think it's the "@ 4.00 GHz" that was concerning, it was the "CPU speed: 4008.14 MHz".
I see numbers like that when running stock. I think it must come from variations in the base clock.

2017-04-13, 21:16   #757
James Heinrich

"James Heinrich"
May 2004
ex-Northern Ontario

3,319 Posts

Quote:
 Originally Posted by kladner I see numbers like that when running stock. I think it must come from variations in the base clock.
It's not that it wasn't exactly 4000.00MHz, but rather that kladner was expecting ~4.2GHz, not ~4.0GHz, hence my suggestion to monitor the frequency in realtime.

2017-04-14, 00:41   #758

"Kieren"
Jul 2011
In My Own Galaxy!

2·3·1,693 Posts

Quote:
 Originally Posted by James Heinrich It's not that it wasn't exactly 4000.00MHz, but rather that kladner was expecting ~4.2GHz, not ~4.0GHz, hence my suggestion to monitor the frequency in realtime.
I did try watching CPU-Z when starting the benchmark. It takes thinning out other CPU users to get a baseline. As mentioned, in the "Sync all cores" option on the Asus board seems to make the frequency (multiplier) jump around a lot. When things were quiet, and the core clock was only occasionally hitting 4200 MHz, moving the mouse of clicking on something would make it peak.

The jump to 42x seems virtually simultaneous with clicking to start the benchmark, at least to human-scaled perceptions.

2017-04-17, 14:12   #759
FSund

Apr 2017

2 Posts

Quote:
 Originally Posted by db597 The 8192K FFT performance looks incredible on this version of Prime95, especially when all 8 cores are thrown at it. Would be good if someone can post results from a similarly priced Intel i7 7700K on Prime95 v29.1 Build 15 for comparison (I expect the i7 is a lot faster per core, but at the end of the day having double the cores may make it a rather close competition).
I have just gotten a 7700k, and I'm in the process of overclocking it now. Will try to report back with benchmarks when I'm done.

At the moment it's looking like I'll have to accept 4.7 GHz for Prime95 runs, any higher and my temperatures get too high. Or to be more specific, at 4.7 GHz have to increase the voltage to 1.280 V to do the the Prime95 torture tests without errors, and at those voltages I get peak temperatures of 85 C, which is a bit too high for my comfort.

 Similar Threads Thread Thread Starter Forum Replies Last Post Xyzzy Lounge 39 2021-03-12 14:19 Oddball Riesel Prime Search 5 2010-08-02 00:11 rogue Soap Box 19 2009-10-28 19:17 Xyzzy Lounge 10 2006-09-28 00:36 Xyzzy Factoring 65 2005-09-05 08:16

All times are UTC. The time now is 07:20.

Mon Apr 12 07:20:39 UTC 2021 up 4 days, 2:01, 1 user, load averages: 2.23, 2.59, 2.31