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-   -   CPU Energy Efficiency for Prime95 (https://www.mersenneforum.org/showthread.php?t=24757)

Uncwilly 2020-10-26 17:33

There is a thread all about the prices that forumites pay for power. It is a bit out of date for some.
[url]https://www.mersenneforum.org/showthread.php?t=22350[/url]

DrobinsonPE 2020-10-27 05:03

1 Attachment(s)
And here is the results of the Ryzen 3-3200G efficiency testing. Following the same procedure, I adjusted the CPU frequency with cpupower-gui and observed the change in mprime output. This time psensor was also used to monitor CPU temperature.

The results were very different this time. Either the motherboard or the CPU did not like the CPU frequency changing because the results were not a smooth decrease in power use and mprime output. Instead the power use and mprime output showed no change for large changes in frequency with sudden step changes in both power use and output as the frequency setting dropped.

Another complication with this test was that I did not have another computer nearby so I had to edit the google sheets form on the computer I was testing. This had a noticeable affect on the results.

I decided to leave the computer running at 2900MHz for a while to see what happens. That gives me a 51% drop in power use with a 32% drop in output.

Total power reduction so far:
i3-9100 - 85W to 46W = 39W savings
GTX-1650 S - 145W to 79W = 66W savings
i5-8250U - 30.5W to 30.5W = 0W savings
3200G - 75W to 36W = 39W savings

See the attached picture for details.

phillipsjk 2020-11-01 07:07

AMD Opteron VS AMD Athlon X2
 
Because I noticed that my "white elephant" machine takes around 96KWh to do a 80-100M LL test (in slightly less efficient low power mode), I decided to compare it to a Athlon X2 5000+ machine that I found more efficient than a Pentium D back in the day.


Don't have detailed measurements that I was able to find, but my "White Elephant" can do a LL test on an 80M exponent in about 21days, at a power draw of 150W/CPU.

Specifications:
[LIST][*] Quad AMD Opteron 6272 (16 cores/CPU, 2.1Ghz, 1.6GHz in low power mode)[*] 128GiB of LP DDR3 ECC RAM,[*] 64GB flash drive for storage (btrfs).[/LIST] Power= Work/Time -> Work=(Power)(Time) -> (0.150kW)(24hours/day)(21days) = [B]96kWh[/B].


The Athlon X2 5000+, drawing only 123W/CPU has a LL runtime of about 144days for an 88M exponent.

Specificatiuons
[LIST][*] Athlon X2 5000+ (2 cores, 2.2Ghz)[*] 2GiB of DDR RAM[*] Live DVD for testing[/LIST] Work=(Power)(Time) -> (0.123kW)(24hours/day)(144days) = [B]425kWh[/B]


Not sure why I was surprised that the old machine got trounced so badly.


Part 2 will be checking how much more efficient my AMD VEGA 56 GPU is once I get it working.

Mark Rose 2020-11-01 18:51

You'll see similar efficiency gains using modern CPUs.

My Intel Skylake quad cores from about five years ago, with total system power at 63 watts from the wall (underclocked and undervolted), can do an 80M exponent in about 3 days, or about 4.5 kWh.

However, I'm no longer running running four systems off one power supply, and now have GPUs and case fans adding to the power consumption.

phillipsjk 2020-11-02 07:49

[QUOTE=Mark Rose;561852]You'll see similar efficiency gains using modern CPUs.

My Intel Skylake quad cores from about five years ago, with total system power at 63 watts from the wall (underclocked and undervolted), can do an 80M exponent in about 3 days, or about 4.5 kWh.
[/QUOTE]

Since GPUs appear to be off-topic in this thread, my next test may actually be [URL="https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=33910,29765"]Intel Core 2 Quad Q6600 (2.4GHz) vs (Duo) E8400 (3.0Ghz)[/URL] (with DDR2).


Did not realize the CPUs in my "White Elephant" may be 9 years old now. It is one of my newer machines.

DrobinsonPE 2020-11-08 01:55

2 Attachment(s)
Here are the efficiency testing results for two more computers. I pulled the 3200G out of the Deskmini A300 and installed an A8-9600 that I already had in it's place. The 3200G is now on a ASRock B450-HDV R4.0 so it will get re-tested for efficency in the future.

Celeron J4105 - This computer did not respond well to adjusting the CPU frequency so I found a different way to increase the efficiency.

A8-9600 - This is not an efficient processor. I knew older AMD CPUs were not that good but I did not expect it to be this bad. The response to lowering the CPU frequency was similar to the 3200G so it is probably the motherboard that does not like the operating system to adjust the CPU frequency.

Total power reduction so far:
i3-9100 - 85W to 46W = 39W savings
GTX-1650 S - 145W to 79W = 66W savings
i5-8250U - 30.5W to 30.5W = 0W savings
[STRIKE]3200G - 75W to 36W = 39W savings[/STRIKE]
J4105 - 20W to 21.4W = -1.4W savings
A8-9600 - 70W to 36W = 34W savings

See the attached pictures for details. In the pictures I am tracking a lot more than just power use changes.


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