LiveOC and Custom Voltage guide by TkGlitch
for Glitch kernel V14
for Glitch kernel V14
Warning!
Overclocking is dangerous and is meant only for experienced users!
Overclocking is dangerous and is meant only for experienced users!
1- Introduction :
The "normal" overclocking system on SGS til now was the addition of some frequency steps past the stock 1GHz step. V13 kernel was using 7 overclocked steps
to push the maximum selectable speed to 1.7GHz.
In V14, less overclocked steps are present, but you can still overclock to 1.7GHz if you want (and if your phone is able to do it), and even up to 2.25GHz as a maximum.
You will need NSTools to use LiveOC and custom Voltage features in Glitch kernel V14.
To begin with, I'll explain you some basic things you have to know.
2- Clocks :
The CPU speed is the result of a bus speed and a multiplier.
Bus speed is linked to and equal to GPU and RAM speed.
The multiplier is per step and hardcoded by the kernel developer.
It does look like that : CPU speed = bus speed x multiplier.
Here are my values in V14 :
1500 MHz = 200 x 7.5
1400 MHz = 200 x 7
1300 MHz = 200 x 6.5
1200 MHz = 200 x 6
1000 MHz = 200 x 5
800 MHz = 200 x 4
400 MHz = 200 x 2
200 MHz = 200 x 1
100 MHz = 100 x 1
LiveOC gives you the access to direct and on-the-fly bus overclocking by 1% steps (150% being the maximum available). I'll say it again : BUS overclocking !
Though, it'll overclock the bus on all the steps at the same time, for the same percentage.
We'll talk about that later.
So if I want to overclock my 1GHz step to 1.1GHz, I'll have to select 1GHz as max frequency, and push LiveOC to 110%.
My bus speed beeing overclocked by 10% will give the following :
220 x 5 (1GHz multiplier) = 1100 MHz.
If you want to go higher than 1.5GHz, it's the same :
Set 1500 MHz as maximum frequency (for example), and push LiveOC. Let's say to 110%. You will get the following :
220 x 7.5 (1.5GHz multiplier) = 1650 MHz.
Pushing it to 114% will give 1710 MHz (228MHz bus) and so on, up to 150% giving 2250 MHz running an inachievable 300MHz bus.
SINCE V14 BETA 6, 100, 200 and 400 MHz steps won't be affected by LiveOC. It should help to stabilize your overclock in most cases.
3- The limits :
THE MAIN LIMIT AND PHONE KILLER IS HIGH TEMPERATURE. WARM IS OK, HOT IS TOO HOT. DON'T PLAY STUPID.
Obviously, so much control over the bus speed, frozen til now to what the kernel developer set, will also give you the ability to find the limits of your chip.
The main clocking limit is generally the RAM, corrupting itself when the bus speed is too high. And since the GPU uses the RAM as well, it'll become crashy too. That's why I have decided to add some steps with a bigger multiplier, to lower the bus for a higher CPU frequency.
The bus speed limits for you will be anywhere between 240 and 270 Mhz, depending on your device potential (higher and lower exists but rare).
Average is 240 MHz.
The CPU speed limits will be anywhere between 1300 and 1800 MHz (higher and lower exists but rare as well).
Average is 1400 MHz.
With that in mind, I wouldn't go too far past 130% (giving 260MHz bus speed).
4- The sweet spot :
What you want when overclocking is to get the best balance for each part. Since the bus is linked to RAM and GPU, you obviously want it as high as possible for gaming, video playing, web browsing etc. (even more now with GPU acceleration in Android 4.0+). Though, as you know already if you've read this guide til now, all steps in V14 are using the stock 200MHz frequency.
So what to do if I want a lower CPU speed with a higher bus/GPU speed ? Simple ! Just select a lower frequency step as starting point.
Let's say we want 250 MHz bus speed, so we'll use 125% LiveOC :
Using 800MHz step, you'll get 1GHz.
Using 1GHz step, you'll get 1.250GHz.
Using 1.2GHz step, you'll get 1.500GHz.
Using 1.3GHz step, you'll get 1.625GHz.
Using 1.4GHz step, you'll get 1.750GHz.
Using 1.5GHz step, you'll get 1.875GHz.
5- The issues :
With a new overclocking system obviously comes some new problems related to it.
With the ability to fine tune the frequencies, you'll find that some frequencies are buggy somewhat, giving low performances. For example, using 115% Live OC with the 1.3GHz step will give some poor performances, when 114 and 116% won't. It could be a NSTools issue, but I think it has more to do with the hardware. It's well known that on CPUs some frequencies or even frequency ranges can be buggy, unstable, or slow. If you encounter that, try to add or remove a percent to LiveOC.
As said earlier, LiveOC will overclock the bus for all steps at the same time by the same amount of %.
Knowing that, you'll have to adapt your voltages for all the frequencies to stay stable, and this for any sensible change on LiveOC percentage.
6- Custom Voltage :
What would be LiveOC without Custom Voltages ?!
I did add leakage values to Glitch kernel features when I saw that some phones were overclocking much better with the right balance between ARM and Int voltages, depending on the phone, with very different results. The leakage value was basically that : balance between the two.
Well, as you probably know if you did read the changelogs, you have now the capacity to overvolt/undervolt both the ARM voltage (the CPU voltage you know well already), and the Int (internal) voltage. The last one is the voltage going to the GPU/memory controller, and will need to be tweaked accordingly to your phone.
As a starting point, here are the Int voltage values I was using for each leakage, adapted for V14 new frequency table :
HIGH LEAKAGE :
1500 : 1.225
1400 : 1.200
1300 : 1.175
1200 : 1.150
1000 : 1.125
800 : 1.100
400 : 1.100
200 : 1.100
100 : 1.000
MEDIUM LEAKAGE :
1500 : 1.200
1400 : 1.175
1300 : 1.150
1200 : 1.125
1000 : 1.100
800 : 1.100
400 : 1.100
200 : 1.100
100 : 1.000
LOW LEAKAGE :
1500 : 1.175
1400 : 1.150
1300 : 1.125
1200 : 1.100
1000 : 1.100
800 : 1.100
400 : 1.100
200 : 1.100
100 : 1.000
Of course, using LiveOC will force you to change these voltages accordingly.
Here are some advices about this :
- Try to stay around 1.225 - 1.250V for your highest frequencies;
- Try not to ever go past 1.300V if you don't want to kill your phone quickly;
- Be VERY gentle when tweaking it as it is VERY sensitive;
- Try to follow a more or less linear curve for Int voltage on OC frequencies;
- Going below 1.000V on 100MHz step will generally kill stability with no battery gain.
This guide may change depending on my decisions related to the Glitch kernel development, or to polish / add things to it.
Thanks to Ezekeel from Nexus S section for these awesome tools.
LiveOC : http://xdaforums.com/showthread.php?t=1288015
Custom Voltages : http://xdaforums.com/showthread.php?t=1331610
23/01/2012 - UPDATED TO REFLECT V14-B1 CHANGES.
09/02/2012 - UPDATED TO REFLECT V14-B3 CHANGES.
24/03/2012 - UPDATED TO REFLECT V14-B6 CHANGES.
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