[Q] SetCpu manual Undervolt vaues - Atrix 4G Q&A, Help & Troubleshooting

Hey guys,
Ok the people who know about SetCpu and undevolting with it...
If I key in UV-values that go further than the slide-bar can take, i.e over -500mV,
does the undervolting actually go under the -500mV??
At the moment I've tried:
216mhz at -725mV [No hang when I run max and min cpu frequency at both 216Mhz]
456mhz at -650mV [No hang when I run max and min cpu frequency at both 456Mhz]
EDIT: I also ran the stress tests at said frequency settings and still no cpu hang or reboot.
I want to see if this goes further, but Im not sure if SetCpu is actually making the UV values go over -500mV.....
Cheers guys
current config: latest Blue Chronic rom, faux 2.1 kernel, carrier unlocked at&t atrix.

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weaz_da_smel said:
Hey guys,
Ok the people who know about SetCpu and undevolting with it...
If I key in UV-values that go further than the slide-bar can take, i.e over -500mV,
does the undervolting actually go under the -500mV??
At the moment I've tried:
216mhz at -725mV [No hang when I run max and min cpu frequency at both 216Mhz]
456mhz at -650mV [No hang when I run max and min cpu frequency at both 456Mhz]
EDIT: I also ran the stress tests at said frequency settings and still no cpu hang or reboot.
I want to see if this goes further, but Im not sure if SetCpu is actually making the UV values go over -500mV.....
Cheers guys
current config: latest Blue Chronic rom, faux 2.1 kernel, carrier unlocked at&t atrix.
Click to expand...
Click to collapse
any jump more than 100mV between steps and it wont do the changes

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The 100mV steps are the limiting factor if you use the higher frequencies which require relatively high voltage not to cause problems. What the OP might be curious about, and what I'm curious about is if I limit my phone to say 600MHz then I can set the voltage of all higher frequencies as low as I want because the phone will never use those frequencies, then I can try to find the true lower bound of the lower frequencies. The problem is I can set the lowest frequency to 0, keeping the 100mv steps, and the phone still runs fine (by limiting my phone to 216MHz), so there is some other rule in effect besides the 100mv between steps rule.
This is something that is limited by the chip itself but I guess that these rules would have to be written in the kernel, so I'm going to post over in the faux kernel thread.
Edit:
I don't have enough posts to post in the developer forum. Can someone copy the jist of my question over in the faux thread or somewhere else appropriate and with marginally high traffic? Thanks.

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I have been thinking about undervolting as well and I was wondering if really does make that big of a difference like some people say? Do you really notice that it improves your batter life?

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Atrix_Owner said:
I have been thinking about undervolting as well and I was wondering if really does make that big of a difference like some people say? Do you really notice that it improves your batter life?
Click to expand...
Click to collapse
The benefits of undervolting are lower power which leads to lower heat and longer battery life. I'm not sure if these power savings translate if the cpu is idle or in some type of sleep mode and the other problem is that all the other components are still using the same amount of power so the real savings might not be much if your phone is mostly idle.
But, my phone idles at 216Mhz and I have almost halved that voltage at that level so the best case scenario is that the cpu is using 1/4 the power it would normally.
I haven't done any testing but I do know there is some savings and we're all here cause we like to tweak things so you might as well undervolt cause it's pretty simple.
I would start with these levels:
1000 - 950mV
912 - 900
750 - 800
608 - 700
456 - 600
312 - 500
216 - 400
The only rule I know for undervolting is the 100mV between steps rule but I know there is some other rule at play as described in my previous post, but I don't know what it is. So really, I'm not sure if the voltages at the lower frequencies are actually being applied.

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Hey thanks for the info. I don't know if I'm doing this correctly. After I undervolted, I clicked "set on boot" and rebooted my phone but I'm not sure if I did it right. For example, when you look at the "1000mhz", on the right it says "Max 1000mV" which is the default setting but shouldn't it be "925mV" because I subtracted -75mv? Look at this pic and tell me if it's like it should be.
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Ya, that's right. That max voltage I think is a misnomer I think it should say default voltage really and that's just there for reference. So, when your cpu is operating at 1000Mhz it is operating at 925mV, with your current setting, it doesn't vary.
If you want to try to push for lower voltages you just want to uncheck set on boot so you avoid getting into a reboot cycle. YMMV on what kind of undervolt will be stable. I gave you my numbers because I think my phone is not as stable as others since it can't handle the 1.45Ghz overclocking kernel.

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My phone isn't overclocked btw and I'm using Faux123's enhanced stock kernel 1.0ghz. I will try to push the volts even lower and see how that goes. One thing that I can say for sure is that when I play GTAIII, my phone doesn't overheat as much as it used to so this defiantly fixed the overheating issue that I was having with almost any game.

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my setcpu doesnt have voltages tab.. y?

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borjok536 said:
my setcpu doesnt have voltages tab.. y?
Click to expand...
Click to collapse
B/c you're not using a custom kernel.
Sent from my CM7 Atrix 4G

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mebster123 said:
The 100mV steps are the limiting factor if you use the higher frequencies which require relatively high voltage not to cause problems. What the OP might be curious about, and what I'm curious about is if I limit my phone to say 600MHz then I can set the voltage of all higher frequencies as low as I want because the phone will never use those frequencies, then I can try to find the true lower bound of the lower frequencies. The problem is I can set the lowest frequency to 0, keeping the 100mv steps, and the phone still runs fine (by limiting my phone to 216MHz), so there is some other rule in effect besides the 100mv between steps rule.
This is something that is limited by the chip itself but I guess that these rules would have to be written in the kernel, so I'm going to post over in the faux kernel thread.
Edit:
I don't have enough posts to post in the developer forum. Can someone copy the jist of my question over in the faux thread or somewhere else appropriate and with marginally high traffic? Thanks.
Click to expand...
Click to collapse
What I gathered from my own experience, experimenting and looking at code is the following:
The 100 mv limit between steps seems to be more of a nvidia guideline for best chip performance. It is not an actual limit in the software, no matter the values you input, they will be applied.
What is indeed limited (and so in the code) is the lowest possible undervolt. In faux's it is 750 mv and clemsyn's (was, not sure if still is) 650 mv.
If you push any voltage past that limit, it won't be applied. Try it for yourself.