My phone runs at 750 mV at 200 Mhz but it can also run 750mV at 368Mhz.
So would it affect my battery to leave the min at 368Mhz? Does the phone still consume the same amount of battery even though the frequency would be higher?
I'd imagine it would draw my current so it'd drain your battery faster.
Yes it will definitely drain your battery faster
Which drain more battery, the undervolt value of -100mV or -140mV?
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Surely it makes little difference on a processor with dynamic clk freq scaling?
Assuming its always clocking at its slowest during idle, which your phone is by default, then reducing the max clock speed during activity just extends the time its chugging away at max speed.
Only way to improve battery life is to reduce the amount of work you ask of your phone, not the speed at which it gets on with it.
For example, if my Desire has to process an image, it can either do that in 1ms at 1GHz, or 2ms at 500MHz, using the same amount of battery, no? At all other times its idling at the same 250MHz.
So the way forward is to reduce tasks, not underclock? And if anything the profile conditions in SetCpu are just one more thread.
Anyone actually noticed better battery performance from SetCpu?
I noticed bader Battery Life! So i dont use it anymore!
I don't think it will give you more battery life to reduce the cpu speed. more important i think is to watch the tasks that run on the background. some apps can drain you battery really fast. i just use advanced task killer and set it to kill apps when i turn my screen off, for me it helps more then lower the cpu speed.
Those apps drain battery by not letting the cpu idle, hence lowering max speed could improve battery life.
Sent from my HTC Magic using XDA App
I have a few questions about OC/UV kernels or rather the theory behind them, particularly the UV part.
My natural instinct is to believe that when the voltage is dropped that the amps would increase so the CPU would still have the same amount of power to run the CPU at a particular frequency. This of course would negate any advantage in UV. I assume that my assumption is wrong or someone that really knows something would have pointed it out.
On the practical side of things, if the above is not true does the phone/cpu use the same amount of power if it is running at 216 Mhz with 770 mV as it does running at 400 Mhz with 770 mV. Same question would also apply to high frequencies that are UV and their relationship to heat generation.
Not sure about smartphones, but with my computer, I can drop 10 watts just from under volting when idle. Under clocking makes an even bigger difference. I'll get some exact numbers in a few mins, this got me wondering lol.
Edit:
At the wall my PC will pull 111 watts @ 1.6GHz idle. @ 4.5GHz it pulls 137 watts on idle.
I wish I had a link I could provide, but the basic science is this (learned this from Calkulin, Ziggy, and trial and error with my evo):
uV:
When you uV your cpu, each frequency step draws less power. For example, a non-uV'd cpu might draw 1300 mV at 1000 MHz whereas a uV'd cpu might draw 1225 or 1250 mV at 1000 MHz. There is no sacrifice in performance. You also get a cpu that runs cooler because it is drawing less power. The combination of these things means better batter life because you are drawing less power (obvious) and generating less heat (heat is one of the enemies of Li-ion batteries holding a charge).
But not all chips are the same, and some tolerate lower voltages better than others. If a particular voltage is too low, you get crashes, reboots, and other things like that because voltages that are too low make things unstable.
OC:
The theory behind OC is that the higher frequencies allow you to complete tasks faster. If the cpu can complete a certain task in a shorter period of time, it will be in use for less time overall, thereby allowing it to return to its idle frequency faster and stay in its idle frequency state longer. Again, this combination increases battery life because the power drawn from the battery is less. You can think of this as a "race to the finish" situation.
For example, if you OC to 1100 MHz, you might complete a task in 1.5s, whereas at 1000 MHz that same task might take 2s. The cpu actually works for a shorter time and returns to idle 0.5s faster. Add this up over an entire day, and your cpu actually spends more time at idle when OC'd than when not OC'd.
Again, just as with the uV, not all chips can tolerate maximum OC and just become unstable. That's why you've seen some G2x chips be able to run at 1500 MHz and be stable, while others can only tolerate 1300 MHz. Instability by trying to OC the cpu too much will lead to the same types of problems as lowering the voltages too far.
OC & uV together:
When you OC and uV, you allow the cpu to run at a higher frequency and draw less power at the higher frequency. This means you get tasks done faster and use less power to complete them, which allows the cpu to return to its idle frequency faster.
This is a real-world hypothetical: Imagine you have a cpu running at 1100 MHZ at 1300 mV and 1000 MHz at 1300 mV. When this is the case, your OC'd/uV'd cpu completes a task faster (in 1.5s rather than 2s) and actually ends up drawing less power than the non-OC'd/non-uV'd cpu because it completes the task faster and returns to idle sooner. When you add this up over an entire charge cycle, you should get better battery life.
How about battery life in Overclocked phones?
Depending on how its clocked, if your needs are speed and usability it lowers the battery life.
Though you can clock it moderate and set the "min" clock frequency down and save battery while its in your pocket.
benjamin336 said:
Depending on how its clocked, if your needs are speed and usability it lowers the battery life.
Though you can clock it moderate and set the "min" clock frequency down and save battery while its in your pocket.
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benjamin336 is absolutely right. I've also found that you have to adjust the settings differently depending on the phone.
There are threads pertaining to adjusting voltages and clocking where people describe what combinations have worked best for them.
99% of the time if you're looking to overclock you're looking for performance meaning 99% of the time you are going to have crappier battery life.
So recently I've become too lazy to constantly charge my Captivate and began to experiment with undervolting/underclocking it. Has anyone found optimal voltage for battery life? I've currently got every step of 200mhz down 100 volts and underclocked to a max of 800mhz. I'm on Semaphore kernel 2.9.5sc.
freshlimes said:
So recently I've become too lazy to constantly charge my Captivate and began to experiment with undervolting/underclocking it. Has anyone found optimal voltage for battery life? I've currently got every step of 200mhz down 100 volts and underclocked to a max of 800mhz. I'm on Semaphore kernel 2.9.5sc.
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There isn't a optimal setting as all phones act different. Testing is the best you can do.
which cpu governor are you running? that may have more effect than underclocking/undervolting on battery life.
user Stempox has a nice post on cpu governors here
http://forum.xda-developers.com/showthread.php?p=28647926
the screen on time and data/gps traffic, and apps that keep the phone awake, do more to effect power drain than other factors. so, if you manage those, and choose the governor that suits you preferences, then undervolting and underclocking aren't needed, IMHO.
you can tweak the governor settings with Semaphore manager, if you really want to do that too.
the thing is, you may end up keeping the screen on longer than you would at higher cpu speeds, which would counter any battery savings. also, undervolting can increase the error rate, which means further delays while phone is awake.
hope this is helpful in your pursuit of fewer charging cycles.
Sent from my SGH-I897
Hi guys, I would like to know something. My phone has a bug and because of it, it's min. CPU frequency is locked at 998mhz (never less), however it's cpu usage is stable (low). So here is my question. What's difference between CPU usage and CPU mhz usage? What's difference (for battery life) between 300 mhz and 5% usage and 998 mhz and 5% usage? How much it affects battery life and general?