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Underclock

Any idea how to underclock I've heard it increases battery life?
Sent from my Desire HD using XDA App

Root > setcpu
Sent from my HTC Desire S using xda premium

If you are using a custom ROM then the ondemand governance will take care of the underclocking when not in use and increase the clock frequency when your usage demands it. That provides reasonable battery saving while not compromising on performance.
Fixing the frequency to a lower limit might increase the battery life but has serious performance issues. Might be handy in critical battery saving situations though.
SetCPU, CPU Master etc.. Such apps can let you modify the upper and lower clocking limits.

Cheers for the replies,where do I get the oc,as for set CPU..you mean one of killersloths kernel scripts?
Sent from my Desire HD using XDA App

Most of the kernels that you can find in the development section have OC scripts already in them.
SetCPU is an app and can be found in the market : https://market.android.com/details?...wsMSwxLDEsImNvbS5taHVhbmcub3ZlcmNsb2NraW5nIl0.

keep in mind that undervolt = giving less power to CPU = can cause damage overtime or reduce battery life.
I mean all these undervolt things don't increase battery time by a huge difference than stock and risking your CPU for just 15 minutes of battery life isn't worth it in my opinion...

Frequency and voltage settings.

Caveats: Every CPU and GPU does not come from the same bin, fabricated on the same date and possibly not manufactured in the same facility. They may each display different physical properties and a wider range of stability than others. What works for me may not work for you.
That being said, I've been stress testing my device with different settings for the past couple weeks trying to find a sweet spot of stability, speed, battery life and heat output.
I'm going to share two setups: my current one that I've stress tested for less than 24hrs but has proved stable through all conditions encountered thus far and my tried and true setup I've used for over a week with no trouble.
Tried and true setup:
Governor - ondemand
Range - 100MHz through 1.6GHz
100MHz - 800mV
200MHz - 825mV
300MHz - 850mV
400MHz - 900mV
500MHz - 900mV
600MHz - 900mV
700MHz - 925mV
800MHz - 950mV
900MHz - 1000mV
1000MHz - 1025mV
1100MHz - 1100mV
1200MHz - 1125mV
1300MHz - 1150mV
1400MHz - 1175mV
1500MHz - 1250mV
1600MHz - 1350mV
Experimental but stable battery saver:
Governor - ondemand
Range - 100MHz through 1.6GHz
100MHz - 775mV
200MHz - 775mV
300MHz - 800mV
400MHz - 800mV
500MHz - 825mV
600MHz - 850mV
700MHz - 875mV
800MHz - 900mV
900MHz - 950mV
1000MHz - 1000mV
1100MHz - 1100mV
1200MHz - 1125mV
1300MHz - 1150mV
1400MHz - 1175mV
1500MHz - 1225mV
1600MHz - 1350mV
GPU setup:
Low power state - 100MHz @ 800mV
High performance state - 400MHz @ 1050mV
Notes:
Custom governors were not stable for me AT ALL! I've found ondemand to be the best one for me and my needs, personally.
100MHz @ 750mV was so, SO close to being stable for me but my phone would routinely reboot in the screen off state. I'm assuming the stress of apps updating in the background, notifications etc was just too much.
As much as I love WidgetLocker (and I really do!), I found it to consume valuable resources, have more pronounced wake up lag and generally contribute to instability.
I use Chainfire3D to run my games etc. at x4 MSAA. As previously stated by Chainfire, the Mali can run at x4 with almost no extra overhead. I imagine that if one doesn't use x4 MSAA, one *might* be able to get away with 400MHz @ the stock 1000mV setting. That being said, I consider an extra 50mV to run at 133MHz faster to be a bargain.
Many games can be run with x16 MSAA with minimal overhead but I've found that for some resource intensive ones, especially multiplayer, they'll slow down unless the GPU is fed at 1200mV but this in turn causes a lot of heat generated so I would advise to avoid turning on x16 MSAA for those that you do find slowing down.
I use and recommend Voltage Control (donate version for extra features!) for setting up clock range and voltage for both the CPU and GPU. It also allows one to set boot settings (at setup or init.d script) and create multiple profiles. I do not recommend init.d script for untested settings as it could cause you issues.
Edit: Not everyone's kernels may support GPU OC/UV or the CPU ranges listed here. I am not responsible if you bork your device.
Here's someone else's method for testing settings:
Here's how I test UV settings.
Turn on everything. Wifi, bluetooth, max brightness, the whole works. This ensures the system is at maximum strain.
Start at maximum CPU clock
Lock the CPU clock (set the minimum and maximum allowed clock to the clock you are currently undervolting)
Lower the voltage by one step
Start a benchmark for a few minutes to see if undervolted clock is stable
If it passes, lower it again go back to step 4
When it freezes up your phone, reboot it and increase the voltage at that clock by two steps and consider it safe
Move to next frequency and go back to step 3.
You reached your lowest clock? Congrats, you should have a well undervolted CPU
Your voltages should always be lowering when your go from the highest clock to the lowest. If it happens that you have to increase the voltage at a lower clock, then also increase the higher clock frequency. I had a few hard locks because of this.
Example.
1000mAh (1GHz) > 900 mAh (900MHz) *< 950 mAh (800MHz) * > 700mAh (600mAh)
The 800MHz voltage is now higher than the 900MHz voltage. Also increase the 900MHz voltage to the same or higher voltage of the lower one.
1000mAh (1GHz) > 950 mAh (900MHz) > 950 mAh (800MHz) > 700mAh (600mAh)
Now that you have it undervolted, you may find that it could hardlock/reboot on you. When it happens do this:
Increase the voltage on all undervolted clocks by one step.
Continue using the device for a day
If the device locks up again, go back to back step 1
If its ok for a day, then every day lower the voltage back to what you had of only one clock (I suggest you go from highest to lowest)
You should be able to find which undervolt caused the reboot fairly quickly and still be able to normally use the phone and keep the rest of the "optimal" undervolts.
Click to expand...
Click to collapse
Sent from my GT-N7000 using xda premium

I don't think UV saves battery. It is display that sucks most of the juice.
You save less than 2% with extreme UV and after a single reboot caused by instability - you lose even more battery.
There's an excellent thread in Nexus S forums - "battery drain benchmarks" (please search it).
I had similar UV settings and my phone never crashed during benchmarks or stress tests.
But it always crashed while installing 100+ apps with app backup restore, restoring backups with TB or MBR, gaming.
After removing UV, it never crashed.
I haven't tested UV with ICS... would see and report if it really saves battery.

Boy124 said:
I don't think UV saves battery. It is display that sucks most of the juice.
You save less than 2% with extreme UV and after a single reboot caused by instability - you lose even more battery.
There's an excellent thread in Nexus S forums - "battery drain benchmarks" (please search it).
I had similar UV settings and my phone never crashed during benchmarks or stress tests.
But it always crashed while installing 100+ apps with app backup restore, restoring backups with TB or MBR, gaming.
After removing UV, it never crashed.
I haven't tested UV with ICS... would see and report if it really saves battery.
Click to expand...
Click to collapse
I'm not sure if you've read everything through carefully or you would have seen that I've covered several of your points.
You also would have seen the method I use for stress testing and would have noted that I aim for four things: speed/performance, stability, power management AND thermal regulation.
While I agree that the display, barring a wonky or misbehaving app, will almost always be the #1 battery drainer - power management will certainly help to conserve battery life.
You also would have seen I mention profiles. There may not be a one size fits all setting for everyone but one can most certainly set up profiles for different scenarios.. Such as TiB backups/restores.
Sent from my GT-N7000 using xda premium

Did you do some benchmarks at the highest speed several times to make sure you are getting extra performance? With this phone I noticed that while the phone wont crash.. .some times performance will drop when running at settings now fully correct.
Sent from my GT-N7000 using XDA

You covered a lot of points but UV is total waste of time.
You get nothing out of it.
http://forum.xda-developers.com/showthread.php?t=1478406
Could you please post your data, how much battery do you save after UV?

Disagree boy, cause with wakelock screen is off, there is significant battery drain, I went to 10 hours life on single charge, due to wakelock.
Normally with deepsleep about 2 days. That's a reduction of 87.5% with screen off. Cpu running @200mhz.
Do the same with undervolting will dramatically increase battery life in that situation. So overal it will be a fraction compared to using the device with screen on, but still significant.
Edit: guess I was wrong here
Sent from my GT-N7000 using Tapatalk 2

baz77 said:
Disagree boy, cause with wakelock screen is off, there is significant battery drain, I went to 10 hours life on single charge, due to wakelock.
Normally with deepsleep about 2 days. That's a reduction of 87.5% with screen off. Cpu running @200mhz.
Do the same with undervolting will dramatically increase battery life in that situation. So overal it will be a fraction compared to using the device with screen on, but still significant.
Sent from my GT-N7000 using Tapatalk 2
Click to expand...
Click to collapse
I actually did the test on Gingerbread.
I set min and max to 200 MHz, activated flight mode and had stock music player running for 3 hours - with undervolt and without undervolt.
To my surprise battery consumption was the same.
May be experts who know about our processor architecture can shed some light here.

Boy124 said:
You covered a lot of points but UV is total waste of time.
You get nothing out of it.
http://forum.xda-developers.com/showthread.php?t=1478406
Could you please post your data, how much battery do you save after UV?
Click to expand...
Click to collapse
I understand where you're coming from, boy.
I don't have data at the moment though I wish I did. But to be honest, it'd be scrambled anyway since whenever I'm not working or mission critical when I need proven stability, I'm testing out all different sorts of settings leading to lots and LOTS of reboots and such!
That being said, anecdotally, I have seen improved battery life for myself but maybe it's a placebo and I could be wrong about it - I have been before in the past. I do feel though that under my normal usage scenarios, I am experiencing less battery drain. It's difficult to quantify though exactly what this is due to since I experiment with kernels, voltages and frequencies.
But if all I'm getting is a 2% boost, man - I'll take it! Like any modder, whether it's min/maxing in a game, working on a car or whatever else, every little bit of a parameter squeezed out is something.
I also feel that you're too caught up on a single aspect, the battery life thing, to the detriment of my overarching holistic goal - efficiency.
Originally I started undervolting and experimenting with frequencies because of thermal output. I had wanted to experiment with x16 MSAA settings, which led to my GPU needing 400MHz and 1200mV which led to lots of heating up which led to me experimenting with everything I could.
Efficiency is what I want. The best performance at the best speeds at the best battery life at the best thermal regulation I can manage.
Now I'm looking at energy efficiency. I'm seeing suggestions that 100MHz may not be as efficient as 200MHz on our Exynos because the tradeoff in frequency power usage isn't worth the longer time spent completing tasks. I'm also seeing that in some situations, a performance best governor targeting max freq may be efficient because less time is spent completing a task and a quicker return to sleep.
I'm just sharing what I'm doing and hopefully others can benefit.
http://forum.xda-developers.com/showthread.php?t=1369817
Sent from my GT-N7000 using xda premium

Wow, thats illogical makes me wonder the math behind it.
Sent from my GT-N7000 using Tapatalk 2

While I appreciate the effort thrown into this, I humbly acknowledge the conclusion is incorrect.
When you lower Voltage slightly, without affecting stability, you pretty much put a toll on the processor for extra "wear and tear" and reduce its lifespan. However, this comes at the reward of reduced current.
So, it should be saving you battery. Underclocking it (safely) is also going to save you battery. And the same thing with different governors, like interactivX compared to regular ondemand, by finishing off processes quicker and reducing the frequency and voltage quicker, and going into Deep Sleep quicker.
I don't have the means to run a Scientific Experiment to prove these claims, nor the time to conduct them. But the majority of "hackers" synonymously agree it saves a noticeable power. These include themers, kernel developers and the casual user. I don't think an educated MAJORITY can be incorrect to the scale of this test's claims.

[Q] Undervolting and cpu binning ?

Hi,
I'm reading topics like franco kernel or faux kernel or cpu binning, and i don't understand what undervolting is using for... And how doing it ?
Plus, i don't understand what cpu binning is for, even if i get there is cpu slow and some fast.
Thanks for your answer !
Sent from my Blade S using xda app-developers app

AutruiP said:
Hi,
I'm reading topics like franco kernel or faux kernel or cpu binning, and i don't understand what undervolting is using for... And how doing it ?
Plus, i don't understand what cpu binning is for, even if i get there is cpu slow and some fast.
Thanks for your answer !
Sent from my Blade S using xda app-developers app
Click to expand...
Click to collapse
The binning decides which voltages you can run your cpu on, those with better "quality" cpu (faster) can run a lower voltage. This does not affect frequencies, so you don't have to worry if you have a nominal binned cpu for example.
As a general guideline, I've read that faster can be undervolted -150 mV, fast -100 mV and nominal -50 mV.
YOUR MILEAGE MAY VARY, SO ALWAYS USE PRECAUTIONS WHEN DEALING WITH UNDERVOLTNING. USE ON YOUR OWN RISK
How to find out which binning you have and more information:
IAmAN00bie said:
Hey fellow Nexus 4 owners, I heard a lot of rumors that the "Nexus 4 uses left-over parts" from the Optimus G. To that end, I want to find out the general quality of our CPUs.
Basically, when Qualcomm makes the APQ8064 chip that you see in our Nexus 4, there are 4 different "types" based on how it meets their quality standards. These are Slow, Nominal, Fast, and Faster. The main difference IIRC between these types is how stable each can handle undervolting. CPUs that are "Fast" for example come pre-configured at a lower nominal voltage than a "Nominal" type CPU, and more so than a "Slow" type. (Does this account for how some people's phones generate less heat? Maybe, maybe not. IIRC, there's like only a -100mV difference between Faster and Slow out of the box, however Faster CPUs should be able to handle lower voltages than Slow-type.)
To find out what binned CPU you have, I recommend the following:
YOU MUST BE ROOTED!
1) Install Terminal Emulator
2) Reboot your phone
3) Open Terminal Emulator, and type:
Code:
su
dmesg | grep PVS
A line should be outputted that tells you what type you have.
For example, mine is NOMINAL. http://i.imgur.com/MUXrs.png
...
Click to expand...
Click to collapse
Sent from my Nexus 4

Is running a lower voltage is dealing with performances or only with battery ?
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AutruiP said:
Is running a lower voltage is dealing with performances or only with battery ?
Sent from my Blade S using xda app-developers app
Click to expand...
Click to collapse
It only affects battery (mostly temperature actually). Basically how good your chip is determines how much voltage it requires to run at a certain speed. Because not all chips are created equal and the manufacturer has to make sure that all of the chips run stable, they set the voltage levels at a conservatively high number. This means that unless your chip is the worst chip that LG expects to produce, you can run your cpu at lower voltages than stock.
It was theorized that the binning of the cpu would be a good indicator of how good your chip is but it looks like it might not be the case.
To undervolt, you have to first flash a kernel that supports it (most custom kernels do) and then download an app like Franco kernel updater or system tuner and you can start adjusting voltages.
Some things to note before you start: if you undervolt too low your cpu becomes unstable which means it will freeze your phone and force it to restart. This does NOT damage anything physically so don't be afraid of it. But this means that you should not have the app set voltages on boot while you are experimenting with them. This would open up the possibility that you set a voltage to an unstable level, forcing your phone to reboot, upon which the app will reapply the instable voltage. This will keep you in a boot loop and force you to re flash the kernel) and/or rom. Just keep it manual until you have set of stable voltages.
Good luck!

AutruiP said:
Is running a lower voltage is dealing with performances or only with battery ?
Sent from my Blade S using xda app-developers app
Click to expand...
Click to collapse
I have a nominal one. The default for the lowest frequency (384, i dont remember exactly) is 900. I made a -150 for all frequencies. it has been running for 3 days without a restart. And for my own feeling, games as well as the whole phone run normally. And when running games, it is less hot than using the default one (900).

Hm, i see, thanks !
Another (and i hope the last one) question, how could i know if i set the voltage to the right value ? Is this any app for testing if it crash ?

AutruiP said:
Hm, i see, thanks !
Another (and i hope the last one) question, how could i know if i set the voltage to the right value ? Is this any app for testing if it crash ?
Click to expand...
Click to collapse
Basically if it runs, you're fine. You want to find the lowest voltage for each frequency at which your phone will run normally. One way of doing this is setting your min and your max cpu frequency to the one that you're testing and adjust the voltage and run a cpu intensive task like a benchmarking or playing a video. However, I find that they are a little more finicky than that and you may find that in normal usage, a voltage that you tested doing that will still crash your phone.
I personally do it over a week or so normally using my phone and gradually adjusting the voltages down to the lowest stable

Does undervolt really affect battery life?

I jus t wondering does undervolt really affect our battery life? How does it work?
When choose to undervolt it affect on performance, isn't it? Slower or stuttering when switch apps? With less energy less performance, does it wrong?
If it is, then how underbolt can improve peeformance better? :confuse
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Judging from my experience UV experimentation doesn't affect battery life, and if it does it's definitely by an inappreciable margin. It does substantially reduce heating issues though especially during high-intensity usage (Spotify, GNow, gaming etc). Just don't overdo it or you wind up rebooting repeatedly--"safe" threshold varies by kernel

It also has no effect on performance, it's completely separate from clock speed.

I UV to lower temperature The N4 is very heat sensitive so you'd be wise to UV if possible, the throttle can kick in very quickly on stock, because of the default CPU behavior(mpdecision+ondemand seem to ramp in a ridiculous manner). I am seeing temps in the mid-low 30s thanks to UV and I'm running turbo mode on Faux's kernel.

(Q) Can undervolting too much cause more heat?

As the title says, can undervolting too much cause more heat than just a little undervolting? I'm at - 175mv on every frequency and my phone usually gets quite warm even with normal use, music, etc. Maybe about 45°c...thanks! (I don't over clock, or play games)
Sent from my Carbon powered AKFAUX fueled monster NEXUS 4

45C is normal for this device, when its in the 60+ range then it's time for concern. Undervolting is in millivolts not volts so the change in temperature and battery is not very significant.

However back in the Nexus S days some genius dev measured that undervolting too much forced the cpu to redo some calculations, which made it use more power than the uv would save. Whether that's what's happening to you I wouldn't know, but it could be.
In the process the dev also found out that undervolting didn't save any noticeable amount of battery. Of course, whether the same goes for our cpu isn't known for sure, but I would guess the same concept applies.
Sent from my Nexus 4 using Tapatalk 4 Beta

One of the main reasons to UV is to prevent overheating/reduce overall temperature increase. So in other words, no. Just don't UV too much (-125 mV MAX)!
Sent by carrier pigeon

your cpu temp is completely normal, a bulls-eye type of normal too. and yes, undervolting too much can cause the phone to work harder, which in turn can cause more heat.