Solved How to make a laptop not idle warmer when plugged in

fruh · Nov 16, 2023

Hi everyone, something's probably wrong with my hands, anyway I've always been able to feel my laptop's keyboard getting sligthly warmer on AC compared to DC, even when left at idle. While the temperature difference was noticeable (from HWinfo too), the performance difference was not
I've never been able to find anything on the web, so some time ago I finally went to the registry and looked for all the power settings I could find that stored different default values for AC (plugged in) and DC (on battery) mode. I will share the few I gathered hoping that it will be useful to anyone interested :)

This list is quite short, but the temperature difference is now negligible, without the PC being noticeably slower. To get rid of the warmer temperatures on AC I matched the values to the default DC ones, so it should be a safe thing to do
Of course it's possible to go the other way around and make the CPU response a bit sharper on DC. Mine is a Dell machine, but I do believe this behaviour is built into windows

Of course this stuff only matters for idle/light usage, it won't improve any machine's cooling abilities (which only come into play at high usage)

Code:

- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\02F815B5-A5CF-4C84-BF20-649D1F75D3D8\4c793e7d-a264-42e1-87d3-7a0d2f523ccd [internet explorer]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\0d7dbae2-4294-402a-ba8e-26777e8488cd\309dce9b-bef4-4119-9921-a851fb12f0f4 [desktop slideshow]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\19cbb8fa-5279-450e-9fac-8a3d5fedd0c1\12bbebe6-58d6-4636-95bb-3217ef867c1a [wireless adapter]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\2a737441-1930-4402-8d77-b2bebba308a3\498c044a-201b-4631-a522-5c744ed4e678 [USB setting IOC]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\2e601130-5351-4d9d-8e04-252966bad054\3166bc41-7e98-4e03-b34e-ec0f5f2b218e [idle resiliency execution required power request timeout]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\2e601130-5351-4d9d-8e04-252966bad054\c36f0eb4-2988-4a70-8eee-0884fc2c2433 [idle resiliency IO coalescing timeout]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\4faab71a-92e5-4726-b531-224559672d19 [devices power down policy]

CPU specific stuff
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00\12a0ab44-fe28-4fa9-b3bd-4b64f44960a7 [lower busy threshold]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00\45bcc044-d885-43e2-8605-ee0ec6e96b59 [processor performance boost policy]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00\4b92d758-5a24-4851-a470-815d78aee119 [processor idle demote threshold]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00\7b224883-b3cc-4d79-819f-8374152cbe7c [processor idle promote threshold]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00\94d3a615-a899-4ac5-ae2b-e4d8f634367f [system cooling policy]
- Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\2e601130-5351-4d9d-8e04-252966bad054 [idle resiliency settings]

Almighty1 · Nov 16, 2023

Well, you can always use ThrottleStop or Intel XTU to undervolt it which works in Windows 10 and 11 but with Windows 11, you can't have virtualization on or else Windows will not have access to the MSR Registers.

fruh · Nov 18, 2023

@Almighty1 you're right, though unfortunately on many machines undervolting is disabled because of security fixes etc. Anyway Xtu, Throttlestop etc act at a lower level than the stuff I posted, which is just a Windows design thing users have no obvious control (or clue) about. Even if you could undervolt and the CPU ran cooler by itself, there still would be a difference in how the OS manages it on AC vs DC

Almighty1 · Nov 19, 2023

Oh well, can't think of anything else now...

fruh · Nov 19, 2023

@Almighty1 don't worry, thanks for your suggestions anyway. What I posted is good only for idle/low usage and it will not make a difference once you start pushing your machine (and that's when throttlestop etc really comes into play)

spapakons · Nov 19, 2023

When running on battery the laptop run slower to preserve battery. When running on AC power it runs at full speed and the CPU is heated more. You can go at Settings, Power and tweak the current power plan (advanced) so the CPU runs at lower of 100% on AC power.

fruh · Nov 19, 2023

@spapakons that's exactly not the point of this thread :)

hdmi · Nov 19, 2023

fruh said:
, though unfortunately on many machines undervolting is disabled because of security fixes etc.

You can unlock it.

spapakons · Nov 20, 2023

fruh said:
@spapakons that's exactly not the point of this thread :)

Well you are looking for a way to reduce heating when on AC power. Reducing CPU speed is one way, so it IS relevant. You can also use a laptop stand with fans. Of course if the laptop is dusted you must blow dust and even replace thermal paste between the CPU and the heatsink.

Almighty1 · Nov 20, 2023

fruh said:
@Almighty1 don't worry, thanks for your suggestions anyway. What I posted is good only for idle/low usage and it will not make a difference once you start pushing your machine (and that's when throttlestop etc really comes into play)

Oh well, I'm trying to fix the problem when the machine is used but because of virtualizaton enabled and Windows 11, I can't use throttlestop. LOL.

hdmi · Nov 20, 2023

On my laptop, turning off Turbo Boost makes the biggest difference each time when I want to keep the fan from spinning up. It's also the quickest way to force it to cool back down again after letting it run warm. In HWiNFO64 you can specify sensor values to automatically trigger a command whenever you need it to, and, it shouldn't be too hard to come up with a script that automatically changes HWiNFO64 settings and restarts it, also whenever you need it to.

Turbo Off:
powercfg SetDcValueIndex SCHEME_CURRENT SUB_PROCESSOR PERFBOOSTMODE 0 & powercfg s SCHEME_CURRENT
Turbo On:
powercfg SetDcValueIndex SCHEME_CURRENT SUB_PROCESSOR PERFBOOSTMODE 2 & powercfg s SCHEME_CURRENT

spapakons · Nov 20, 2023

I think it is best if you clean dust from the fan vents, or even better remove the cover and remove all dust inside. Since you would have removed the cover it is a good idea to replace thermal paste. I know, not all laptops give easy access to the CPU to replace thermal paste, you can ask a professional for a reasonable price to do it for you. The next step is to always use a stand with fans and of course avoid placing the laptop on your lap, on a blanket, on the sofa and other places that can trap heat and warm it faster.

To blow dust from the fan vents you can use an air spray or an air blower. If the dust is stuck, use a medium soft (not too soft) painter's brush or toothbrush to scrap it before blowing. The same process (first brush then air) is recommended for removing dust inside if you decide to open the cover.

fruh · Nov 20, 2023

@spapakons it is not relevant because I'm talking about idle usage, as explicitly specified in the first post. Of course what you're saying about keeping the cooling system clean is always good practice. I have now edited the thread's title for clarity

@Almighty1 that's a big oof lol. You might try to look into the hidden power settings for CPU responsiveness (there are a few) which do not help with sustained heat output but do make a difference for load spikes

@hdmi I did disable turboboost in my BIOS since it did more harm than good especially at low usage, thanks. I've also found out that disabling hyperthreading helps, but I did that in the BIOS too. I will look into what you've suggested since I didn't know about it anyway :)

Berton · Nov 20, 2023

If the battery is easily removable do so and plug in the AC adapter while using it for a few hours, see if the noticeable heat is reduced. The process of charging the battery also produces heat.

spapakons · Nov 20, 2023

Disabling TurboBoost and HyperThreading limits CPU speed, just like I suggested, and help keep it cooler. You can just set the maximum processor state below 80% in Advanced Power settings without having to disable TurboBoost and HyperThreading.

fruh · Nov 20, 2023

@Berton unfortunately my laptop is new enough not to have the removable battery

anyway yours is a good idea but I had higher idle temperatures on AC even when just idling and everything else taken care of (100% battery etc). It's just some good(ironically) old(not so ironically) Windows design stuff, as the difference between hidden AC and DC power settings shows

@spapakons I did try limiting the maximum processor state but it doesn't do anything for idle conditions. What you are suggesting is right but not for what I'm talking about. I don't know if limiting maximum processor state has an influence on turboboost but disabling it altogether doesn't affect performance for my tipical usage

spapakons · Nov 20, 2023

Whatever works.

hdmi · Nov 21, 2023

fruh said:
@hdmi I did disable turboboost in my BIOS since it did more harm than good especially at low usage, thanks. I've also found out that disabling hyperthreading helps, but I did that in the BIOS too. I will look into what you've suggested since I didn't know about it anyway :)

In the commands I posted, substitute SetDcValueIndex with SetAcValueIndex if you want to turn on/off Turbo Boost when the laptop's power supply is plugged in.

Almighty1 · Nov 21, 2023

fruh said:
@Almighty1 that's a big oof lol. You might try to look into the hidden power settings for CPU responsiveness (there are a few) which do not help with sustained heat output but do make a difference for load spikes

On my system if I leave it on modern standby, the system will actually sleep so I have to turn off modern standby so it uses S3 instead and I have my fans running at 5100rpm or full speed, otherwise the cpu will throttle. I am also running in high performance power profile which is needed to turn the sleeping part off. It's actually the older laptops that have the removable battery and not the newer laptops. Which hidden power settings are you referring to? As by default, I will only see the Dell and Balance. But by turning off modern standby and unhiding, I can see: Dell, Balanced, High Performance, Power Saver, Ultimate Performance profiles..

hdmi · Nov 21, 2023

fruh said:
@spapakons I did try limiting the maximum processor state but it doesn't do anything for idle conditions. What you are suggesting is right but not for what I'm talking about. I don't know if limiting maximum processor state has an influence on turboboost but disabling it altogether doesn't affect performance for my tipical usage

Same here. When my laptop either is idle or is doing nothing much (e.g. listening to an internet radio stream whilst reading a few forum threads), the fan still annoyingly spins up rather frequently excepting only if Turbo Boost is off, and, all the other power settings have very little to no effect on this specific behavior type. All my hidden power settings are unhidden BTW. This Powershell script generates the necessary batch code to unhide them all:

Powershell:

$s = @{}
Get-CimInstance -Namespace root\cimv2\power -ClassName Win32_PowerSetting |% { $s[$_.InstanceID.Substring(24,36)] = $_.ElementName }
Get-CimInstance -Namespace root\cimv2\power -ClassName Win32_PowerSettingInSubgroup |% { $guid = $_.PartComponent.InstanceID.Substring(24,36); ":: $($s.$guid)`npowercfg -attributes $($_.GroupComponent.InstanceID.Substring(32,36)) $guid -ATTRIB_HIDE`n" } >unhide_all_power_settings.bat