[SOLVED] Any way to underclock cpu when I'm not playing games?

ian353

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Jul 31, 2017
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Hello, I was curious if someone could direct me toward the information I seek. To begin with I have an i7 7700k @ 4.2 (3.9 idle w/ speedstep ) on an Asus PRIME Z270-AR mobo. I'd like to figure out if it'd be possible for speedstep to go down to around 2.5-3 ghz while my pc is just idling or I'm watching a youtube video. I looked around in the bios for a little bit, and the only thing I was able to do with speedstep was enable or disable it. I doubt it's possible to achieve the level of control I desire without some nefarious modifications, but any information or links to articles would be greatly appreciated.

Thanks!
 

Darkbreeze

Titan
Moderator
Go into the control panel power options. Click the "change plan settings" link next to your current power plan (Performance, power saving, balanced, etc.). Next, click on "change advanced power options". Then scroll down to processor power management and expand it. Set the minimum to 8%. Leave the maximum at 100%. Save settings and exit.

In the BIOS, make sure Speed step is ENABLED, BUT, disable Speed shift. Save settings and exit BIOS. Speed shift, on a lot of systems, does not allow speed step to work correctly. I don't think it was ever properly implemented on a lot of motherboards.
 

Darkbreeze

Titan
Moderator
To me, sounds like at idle it is not dropping to normal idle speeds. When people set the power profile to performance, that puts the min and max both at 100%, so even with Speed step enabled it usually won't ramp down. At least, I think that is what they were complaining about. I could be wrong, and they are looking for some other configuration change but I think that is the solution they are needing.
 

boju

Glorious
Yeah maybe

How i understood it is when doing less intensive tasks to underclock to save on electricity and heat i suppose. Neither would really be a worry though, i doubt power bills would change much and there wouldn't be much heat produced from either cpu or gpu.
 
with everything set to default/Auto in BIOS, and WIndows Balanced power plan selected, my 7700K jumps from 800 MHz-1200 MHz when simply reading forums, to 2000-3500 MHz momentarily when opening/closing apps, to 4500 MHz under load. (Exactly as it should) Base clock is 4.2 GHz, but, it will/should idle down to 800 MHz when nothing is going on, or, someone has been tinkering with BIOS, Speedstep /min clock speed settings to stop it...

(With Intel's XTU, it now also turbos up on all cores to run 4.7 GHz on all cores with just a 5C extra peak load temp, at about 78C in Prime95/small FFTs...)
 

ian353

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Jul 31, 2017
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Go into the control panel power options. Click the "change plan settings" link next to your current power plan (Performance, power saving, balanced, etc.). Next, click on "change advanced power options". Then scroll down to processor power management and expand it. Set the minimum to 8%. Leave the maximum at 100%. Save settings and exit.

In the BIOS, make sure Speed step is ENABLED, BUT, disable Speed shift. Save settings and exit BIOS. Speed shift, on a lot of systems, does not allow speed step to work correctly. I don't think it was ever properly implemented on a lot of motherboards.
Wow, that was easier than I expected haha. Thanks for the help man!
Thanks to everyone who joined the discussion as well.
 

ian353

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Jul 31, 2017
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My tests show this doesn't make any noticeable diff in heat or power consumption.
Yeah I'm monitoring my temps right now, it makes a slight difference of a few degrees c, and it lowers the fan speed so that's enough for me. I was expecting this solution to be more effective, but it is what it is. I'm guessing the cpu is set to receive a certain amount of voltage regardless of clock speed, and even if the voltage is dynamic it'll never go under a certain threshold causing the temps to not really be affected. Just my thought on the matter, I might try to play around with voltage and see what results I can get.
 

InvalidError

Titan
Moderator
i doubt power bills would change much and there wouldn't be much heat produced from either cpu or gpu.
On my i5-3470, there is a ~8W difference between 5% idle and 100% idle. At $0.10/kWh, that's about $8/year if you leave your PC turned on 24/7 and don't need the higher clocks most of the time. Not much, but still nice to have when it requires practically zero user effort.
 
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ian353

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Jul 31, 2017
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Im not sure how low windows can adjust cpu frequency but try change maximum processor frequency in power plan.

https://www.tenforums.com/tutorials/95574-change-maximum-processor-frequency-windows-10-a.html

If you try let me know how you go
Yeah thanks, that tutorial was pretty similar to what I was looking for. The minimum frequency Darkbreeze posted was exactly what I was looking for, but a useful article regardless. I did end up making a custom plan for both gaming and watching videos, seems like the easiest way to do it. Now I gotta figure out if I can write/steal a script to activate each of the power plans instead of going through the windows menu crap.
 

Darkbreeze

Titan
Moderator
Yeah maybe

How i understood it is when doing less intensive tasks to underclock to save on electricity and heat i suppose. Neither would really be a worry though, i doubt power bills would change much and there wouldn't be much heat produced from either cpu or gpu.
Less intensive tasks would ALREADY tend to run at lower clocks and on fewer cores, so setting the minimum processor power profile to a number less than 100%, I normally like 8%, generally DOES do all those things.
 

Darkbreeze

Titan
Moderator
There is literally NO need to have different power plans. One plan, with the settings I mentioned, offers exactly the same performance in gaming as having it set to 100/100. The CPU cores jump to full speed so fast, and they do so generally anytime there is even a hint of a full load coming, that you would never know the difference anyhow EXCEPT when the system is at idle. It would be impossible, except maybe on some sort of synthetic bench, to even discern a difference in performance reaction times.

Just leave it at the 8/100 setting. If you are gaming, it's not going to drop below 100% unless that core is not needed or is not being used anyhow. Good luck.
 

InvalidError

Titan
Moderator
There is literally NO need to have different power plans. One plan, with the settings I mentioned, offers exactly the same performance in gaming as having it set to 100/100.
While generally true, Windows likes to bounce threads between cores and if there isn't enough load to keep all cores active, you have situations where a performance-critical thread is bouncing between sleeping cores and getting stalled for tens of microseconds. People have reported stutter or other performance problems when cores are allowed to clock or power down that do get solved by the Performance preset most likely due to this reason.

Apart from those few cases, Balanced is just as good as Performance.
 

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