Question Which two cores to disable on my Ryzen 5800X to lower energy consumption ?

[DFace1_2]

Hi all.

I've had a Ryzen 5800X for about 3 years now and am trying to minimise energy usage in my new flat because energy bills are insane.

I'm not bothered about playing the latest AAA games and I've downgraded from a 1440p monitor and a
6950 XT to a 1080p monitor and an RX 7600. I was looking into selling my Ryzen 5800X and getting a 5600X but then realised that was silly when I can put it in eco mode or disable some cores to theoretically achieve the same result. But I haven't been very impressed with the performance change in any of the eco modes using my MSI B550-A Pro board, so my question is..

What are the best 2 cores to disable to effectively turn my 5800x into a 5600x with also reducing the temperature in mind? I know the cpu is a fully packed CCD. Would disabling ANY two have the same result? I know core 6 is the strongest core so probably want to keep that one on.

Thanks.

 

[helpstar]

don´t expect too much out of it

about 60W less @full load, 10hours a day, 7days a week, should
so 0,06kWh, 0,6kWh a day ->220kWh a year. I would say this to be the maximum of what you could expect in reducing the costs.
max. load 24/7 a year: 0,06kWh x 24 x 365-> 526 kWh

let´s say 50cent per kWh per year:
max. load 526 -> $263
full load 220kWh ->$110
usual load average 37kWh ->$18,5

 

[DFace1_2]

Thanks! Just want to eek out the savings where I can. Would it be the same temps regardless of which cores I disable?

 

[helpstar]

Ryzen master just marks the best and preferred cores for overclocking. I think for the OS it´s not relevant. Would just disable the unmarked cores
https://www.anandtech.com/show/15137/amd-clarifies-best-cores-vs-preferred-cores

the temperatures will be most likely similar, if the applications you use are not using 8 cores at all

 

[CountMike]

I don't think you can disable just chosen core(s) nor that would help much or even little, they receive power even when disabled. You can disable whole block of 4 in BIOS (Ryzen comes with 2 sets of cores (3 or 4) on one die). Easiest way and also able to change on the fly is in Run > MSCONFIG > Advanced options > Number of processors where you can put even just one core although can't choose which one. You can always change that if required.

 

[drea.drechsler]

Hi all.

I've had a Ryzen 5800X for about 3 years now and am trying to minimise energy usage in my new flat because energy bills are insane.
....

Ryzen 5000 CPU's are already remarkably energy efficient. The way the algorithm works it only utilizes a core when it's actually needed for processing. It moves small processing tasks around to other cores to balance heat loads and actually turns off those not needed so they can cool off, saving energy in the process.

It all happens very fast, much faster than monitoring programs can show directly in core clock charts. HWMonitor does show it in it's sensor reports though: look for sensor reading called "Core C6 Residency". That's the percent of time a core spends in C6 performance state, which is turned off.

Disabling cores won't likely realize any energy savings unless your applications fully utilize all available cores all the time. Even that's doubtful since disabling two cores means you're simply losing 1/4 of available performance making the processing task that much longer to complete on the remaining cores, using the same amount of energy over that longer time period.

Your best way to reduce peak energy consumption is to enable PBO and use a negative boost clock offset or disable boosting altogether. That may be do-able in RyzenMaster and definitely is in BIOS assuming you don't have an A320 or A520 motherboard. There may also be an EcoMode setting in BIOS (maybe RM too) which does similar. While this will reduce peak energy consumption the average over time for a given processing task may not see any benefit since, once again, it simply takes longer to complete intense processing tasks.

Other things to do that may be far more productive are to disable any and all RGB and LED lights, disable unused motherboard circuits in BIOS (WiFi, serial and parallel ports, unused USB and SATA ports in particular). And much bigger savings may be had by disabling unneeded services you don't want running in the background. They wake up during idle periods and use up energy for CPU cycles, internet accesses and drive accesses for things that you may not need or even want . There are many motherboards that download and install services that do this sort of thing constantly to keep their utilities up-to-date, and report system useage metrics for their benefit. One other easy thing to do is to find WindowsUpdate settings and delay updates in its advanced settings.

And shut off fans or remove them altogether. If you have a water cooling setup change to a HUGE heatsink with a slow moving fan...or even a passive open air arrangement. That's the best way to realize energy savings from hobbling a processor by reducing cores and clocks, just monitor temperature and make sure to not take that too far.

 

[geofelt]

To measure your electrical consumption accurately , buy a kill-a-watt device.
Then experiment and measure the actual $ savings.
One simple way would be in windows power management, reduce the max cpu from 100% to say 80% and use a balanced profile.

I would characterize this as an interesting experiment and not likely to result in any meaningful electricity savings.