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Mini Overclocking Guide

Mini Overclocking Guide​
NOTE: The Steps Below were Tested on Froyo Roms. I have found different and perhaps better ways to test stability with CM7 Roms so I added a section for that too.
You can still use Stability Test but I don't use it too often anymore for CM7.
Programs Required for testing:
#1 Stability Test
#2 Neocore (please note that some kernels are not FPS unlocked meaning that the frame rate will not go over 56fps so make sure to compare apples to apples when testing different kernels).
For overclocking/undervolting you can use either Pimp My CPU or Voltage Control
Intro:
I posted this Guide in ROM thread but decided it might help someone trying to get a head start overclocking...just a reference not a bible.
First of all, please realize that no two CPUs are created equal. Just like with PC Overclocking, there is the luck of the draw involved here so just because one person can do 1.4Ghz it does not mean you will be able to do so nor it means that my UV settings will work for you.
Achieving 1.2Ghz should be feasible for almost all users since most of the code for it was already done by Samsung themselves. After that point though, it is a matter of luck. Many users can do 1.3Ghz but getting into 1.4Ghz the chances of stability drop dramatically.
Please note that with CM7 Roms it seems a LOT more people is able to hit 1.4Ghz and even 1.5Ghz fully stable. 1.6Ghz is also working although not as common. It is easier to use it if you select 1.6Ghz as the ONLY frequency but of course battery life will be affected.
So, start at 1.2Ghz and try to achieve stability with the lowest possible UV settings you can get to improve your battery life then when fully stable, go for a bit more speed if you like until you find your limit.
Process:
The following is the process I use to get 100% stability. Of course, you can use your own or tweak as you like as this is hardly the ONLY TRUTH of overclocking…I just hope it gives you a good idea on how to achieve stability.
I normally use these settings for 1200Mhz:
1200Mhz @ -100
1120Mhz @ -100
1000Mhz @ -100
900Mhz @ -100
800Mhz @ -100
400Mhz @ -100
200Mhz @ -100
100Mhz @ -100
After setting those up , click the Apply Now button but do not save to the Boot settings until you are sure they are stable for you.
To check stability I first run the Stability Test program and let it loop about 30 times or at least 20 of the CORE (not the RAM).
If it fails give it another shot if it fails again then it is time to adjust the voltages for 1200Mhz.
My experience has been that Stability Test crashes to the home screen when it needs more voltage so if it crashes for you change the UV to -75 and test again.
When you are able to pass that test , you can go to Neocore and try looping Neocore and let it running for about 5 to 10 minutes.
If Neocore freezes, at least for my phone, it means that voltage is too high so I need to drop the UV.
Right there is where the whole trick is. Trying to find what UV voltage is enough for Stability Test to pass but still low enough so that Neocore does not freeze.
This takes a lot of trial and error specially when going for 1.4Ghz!
Another thing is that the UV setting for the frequency below the one you are going for, like 1120 and 1000 for example, do have an effect on the stability you are trying to achieve on 1200Mhz because the phone does not seem to like big voltage jumps .
Some times changing the voltage for the frequency below the one you are adjusting is a good way of achieving stability.
This becomes more important when for example you find out that changing 1.2Ghz to -50 gives you stability for Stability Test but then you need -75 in order to pass Neocore test. What do you do then? What I have done with relative success is , use -75 but then increase the voltage to the frequencies below 1200.
For example if I had
1200Mhz @ -75
1120Mhz @ -100
1000Mhz @ -100
I would change it to:
1200Mhz @ -75
1120Mhz @ -75
1000Mhz @ -75
then test Stability Test to see if those changes help you pass it without having to increase the voltage for 1.2Ghz directly thus avoiding the Neocore freezing issue.
Another process some users are doing is just run Neocore for about 30 minutes and it seems to be a good alternative for some. Guess it all depends on your particular phone.
So, as you can image, this means a LOT of trial and error and restarts of your phone. For 1.2Ghz it should be painless but if you want to go higher, prepare to do a lot of the steps above.
Another thing to consider is that some phones seem to work better with kernels that only have one top speed after 1Ghz as opposed to kernels that offer multiple speed options so this is yet another variable to work with.
Also, remember that to restart your phone, there is no need to pull out the battery. Just press and hold the Volume Up and Power button and it will restart.
I am sure this guide can be done a lot better and will be glad to add or edit with any recommendations you can offer.
I hope this helps some of you trying to push your phones to the limits and have fun!
UPDATE for CM7 Users
With CM7 what we considered THE holly grail of speeds, 1.4Ghz with Froyo Roms suddenly became a VERY common thing.
I have no explanation as to why but a LOT of users are able to get 1.4Ghz and even 1.5Ghz perfectly stable on CM7 and the phones just fly at those speeds. Some are also able to get 1.6Ghz stable but that is harder.
Setting only one speed like 1.6Ghz dramatically increased the stability as well. Just a hint for you guys wanting to do some benchmarks.
You can use a program like Pimp My CPU or Voltage Control to set the voltages and the Maximum and Minimum speed.
Now while the Steps at the beginning of the guide (for Froyo roms) should be fine for CM7 as well ...I have noticed, at least with my phone , that a video player called Moboplayer is VERY good for stability testing CM7. In fact, I do not even use Stability Test any more since I moved to CM7.
When the voltage is a bit low on my screen it creates some artifacts, usually green spots that come up and go in random areas until it freezes.
My actual favorite player for CM7 is Dice Player because for me it plays 720p files better but I like moboplayer a lot as well specially because of the artifacts it shows when I am not stable so it is a quick way to tell the settings are not going to work.
Another thing I love to use if the Riptide Game (tegra 2 game) with Chainfire 3D plugin to make it work on our phones. That game will just close without warning when my speed is unstable. So I just let it running the demo on its own for about 10 minutes.
So basically, I use Moboplayer and Riptide to test my stability and with those tests my system is ready to go and takes less time than the steps I used to do.
Of course you can come up with your own preferred tools since our phones are quite unique and seem to have their own personalities.
It seems some users are having luck with my settings so here are my settings for 1.6Ghz This is for GLITCH kernel (V10C VC). Remember that each kernel has different voltages so instead of giving you a minus value like -100 I will give you the actual voltage I am using for each speed.
1.6Ghz - 1425mV
1.5Ghz - 1400
1.44 - 1325
1.4Ghz - 1325
1.3Ghz - 1275
1.2Ghz - 1275
1.0Ghz - 1200
800Mhz - 1100
400Mhz - 950
200Mhz - 850
100Mhz - 850
For Governor I normally just have Smartass and the Scheduler is NOOP.
Not that while for 1.6Ghz my current setting is either -50 or -75, if I were to select only 1.6Ghz as my max and minimum speed, I am then able to lower the voltage to -100 perfectly stable. Just an interesting thing for you to play with.
Important Note for CM7 users getting many FCs like google service or android service.
CM7 has a much smaller data space for application installs and every time I get to that limit my phone gets crazy with FCs. You can check that by going to your applications and launching the TERMINAL application then type df (in lower case) and pressing Enter.
Look at the top table listed for /datadata and make sure you have some available space.
As long as I keep that from filling up (in fact I prefer to keep it around 60% max to give me some room) my phone works like a charm.
You can use an app like APP2SD to move application data to the SD card to free up space.
Have fun and enjoy your pumped up phone!
UPDATE 12/30/2011
CyanogenMod 9 (ICS) users with Glitch kernel using LiveOC you can use my settings as a starting point.
This is what I use for 1603Mhz
Voltages:
ARM voltage
from 1500 to 1200 = 1.5V ; 1000 = 1.375V ; 800 = 1.250V ; 400=1.100V ; 200=950mV ; 100=900mV
Int from 1400 to 1200 = 1.2V ; 1000 = 1.15V ; 800 = 1.125V ; 400=1.100V ; 200=1.100V ; 100=1.000V
Then 123% LiveOC using 1300MHz step (giving you 1.6GHz)
Governor I am still testing but usually Smartass V2
You can of course use it as a starting point for lower speeds if you like.

Nice man. Saves alot of frustration with this.

Awesome! Thank you!

You are the OC master, Shaolin.
Sent from my SAMSUNG-SGH-I897 using Tapatalk

I wish I was a master indeed but I just have a lot of patience I guess to test ..and test...and crash..an test some more

I think I saw a post that said that any temperature below 56 degrees Celcius is fine for the captivate. I still start to worry though if it reaches 50 during a stability test, what's your opinion?

I noticed that mine when it its 50C or so for any reason (battery temp IIRC) it stops charging so that is where I normally draw the line. If I cannot keep it under that I dont feel comfortable.

That 50 is pretty high, at least for me. Even with stability test going for an hour or so at 1400, I only hit 46. Haven't seen anything higher
Sent from my SAMSUNG-SGH-I897 using XDA Premium App

Depends on ambient temp of course...you cannot compared devices temps without knowing the ambient temp. In any case, I saw that when I was using the first Trident kernel. That one even made my screen feel very hot...kinda scary lol
Right now, the only app I have that makes my phone stop charging, even when temp is low, is the Justin TV viewing app....weird. I even ran the phone at 600Mhz only to make sure.

AReynante said:
That 50 is pretty high, at least for me. Even with stability test going for an hour or so at 1400, I only hit 46. Haven't seen anything higher
Sent from my SAMSUNG-SGH-I897 using XDA Premium App
Click to expand...
Click to collapse
I was testing out 1500 1400 is fine for me with -100 for each value. 1500 is a different story since I haven't managed to find a stable combination yet (that doesn't reach 50 degrees Celcius).

Sweet. Are you getting to 50C with a specific app? I only get there with some streaming apps but I really only use 1.5 for fpse emulator for example.

I don't have an app that tells me the temperature so the only time I know is if I do a stability test. I'm not sure if I really have a need for 1500MHz since I don't use emulators much but it's more of a "yea my phone can do it" kind of accomplishment - unless I'm missing out on some other benefits of 1500Mhz over 1400Mhz besides possibly more smoothness.

zuN! said:
I don't have an app that tells me the temperature so the only time I know is if I do a stability test. I'm not sure if I really have a need for 1500GHz since I don't use emulators much but it's more of a "yea my phone can do it" kind of accomplishment - unless I'm missing out on some other benefits of 1500Ghz over 1400Ghz besides possibly more smoothness.
Click to expand...
Click to collapse
Lol 1.5 terahertz I want that phone!

studacris said:
Lol 1.5 terahertz I want that phone!
Click to expand...
Click to collapse
Wow didnt notice that....thats Fing awesome!

Stability Test question
Hey Shaolin,
Just a quick question here, when you mention running stability test through 30/50 runs, are you referencing the RAM runs or the core runs? Just checking, since the RAM runs complete within a few minutes whereas the core runs take closer to half an hour, etc.
Thanks for posting the guide, much appreciated!!!

Since the new version I am only doing 30 of the core runs since it seems to take longer than before.
You are welcome amigo

shaolin95 said:
Since the new version I am only doing 30 of the core runs since it seems to take longer than before.
You are welcome amigo
Click to expand...
Click to collapse
Hey mate, maybe you can add this to your guide as I thought before that stability test and several runs of new core, nenamark, etc...that after passing those tests you're probably stable but what I found out that I can pass those tests without problems and just recently those test are not enough for you to be sure if you are really stable what I have found is to run or record in your phone video cam in its highest resolution about 720p for 200mb worth of data if your phone won't freeze then it's pretty stable you can delete those files afterwards.

Indeed each phone and user can find specific things that work for them, for example with my phone I can just use mobo player and play some videos and I get artifacts when voltage is low or I had a game that with low voltage will always freeze at the same spot yet some user do not have the same effect.
I guess I can add a small list of other possible quick tests like that video one you mentioned as alternatives

I found out another way to test stability which is to do a batch operation of backing up apps with TiBu. I'm not sure what it implies if it crashes though

Hi shaolin95, can I link this post in my VoltageControl thread? (with credits ofc)

[Q] SetCPU vs. Voltage Control, and what are some recommended settings?

My understanding is most people prefer Voltage Control, but SetCPU allows for specific under/overclocking profiles that can increase performance without killing battery life.
If someone could direct me to popular, trusted settings, I'd appreciate it. I'm not a heavy user or power user, so I'm looking for something that just works well. I don't care about benchmarks and things of that nature.
I'm sure this has been discussed, but I was unable to find posts that didn't concern user-specific issues.
Thanks,
Wyatt
EDIT: 53 views and no replies. I guess I'll experiment for myself. Wish me luck!

gnarlynewport said:
EDIT: 53 views and no replies. I guess I'll experiment for myself. Wish me luck!
Click to expand...
Click to collapse
That's really all it comes down too...experimenting and finding out what works best on YOUR phone with YOUR configuration...
GOOD LUCK!
ps... have been very stable with OC'd to 1.4
-25 down too 200
-100 on 100
bfq and conservative

I use VControl myself...i like the UI.
For Performance: 100-1.4GHZ (1.5 works too, but is WAY overvolted, and 1.6 is extremely unstable), -100mV from 100-1000 MHZ, -75 for 1.1-1.4GHZ.
For "Battery Life": (i really don't see a difference...) 100-800 MHZ (anything below 800 is painfully slow), -100mV across the board.
I leave schedulers and governors at their stock settings, the only time I change anything is to set the gov. to Performance on Performance for max Quadrant scores.

kvswim said:
I use VControl myself...i like the UI.
For Performance: 100-1.4GHZ (1.5 works too, but is WAY overvolted, and 1.6 is extremely unstable), -100mV from 100-1000 MHZ, -75 for 1.1-1.4GHZ.
For "Battery Life": (i really don't see a difference...) 100-800 MHZ (anything below 800 is painfully slow), -100mV across the board.
I leave schedulers and governors at their stock settings, the only time I change anything is to set the gov. to Performance on Performance for max Quadrant scores.
Click to expand...
Click to collapse
How many Mhz levels are you selecting? In my experience anything above 5 and it WILL NOT clock up to the higher settings. Maybe thats why you notice no difference in battery life?
For instance if you had say 100, 200, 400, 800, 1000 and 1400 you will reace 1000mhz only
if you had 100, 200, 400, 800, 1400 you would reach the 1400mhz. ive tried many combos and 5 or less was the max it would use (voltage control app, im sure setcpu would most likely be the same)

How many slots does the imnuts kernel support?
Sent from my SCH-I510 using Tapatalk

I started using SetCPU, and I think I prefer it.
Quick question, it seems like rebooting is unnecessary for the changes to take effect, is that true?
Overclocking definitely worked. I got 1853 @ 1200mhz in Quadrant, up from 1600.
Edit: now 2025 @ 1300mhz / 1300mhv
2nd Edit: Late last night, I was using a stability test in one of the apps, but I can't for the life of me remember which app or how I found it. Now I'm using StabilityTest from the market. What's a safe cpu temp for these phones? I'm getting 32 degrees under full load in an air conditioned environment.

gnarlynewport said:
I started using SetCPU, and I think I prefer it.
Quick question, it seems like rebooting is unnecessary for the changes to take effect, is that true?
Overclocking definitely worked. I got 1853 @ 1200mhz in Quadrant, up from 1600.
Edit: now 2025 @ 1300mhz / 1300mhv
2nd Edit: Late last night, I was using a stability test in one of the apps, but I can't for the life of me remember which app or how I found it. Now I'm using StabilityTest from the market. What's a safe cpu temp for these phones? I'm getting 32 degrees under full load in an air conditioned environment.
Click to expand...
Click to collapse
I just switched over to Setcpu as well. It seems to work better for me also. I can now select 6 levels instead of the 5 before in voltage control and I also noticed that the set on boot on voltage control did NOT work but it DOES work in setcpu!! Im happy!

Haven't tried Setcpu yet, but I preferred Pimp my CPU over VC when I was using Miui on the Fascinate.
Sent from my SCH-I510 using XDA App

Juice Defended Ultimate Settings?

I was wondering if anyone had figured out a close to perfect combination of the settings in JDU to get the best battery life and still maintain full functionality.
I have my email sync every 30 minutes, have background data on, and use games a lot. With the extended battery I get a full day of use out of it but I feel like I should get more. I mean the screen is on a lot and I'm playing online games so that definitely is a factor. I'm worried maybe the battery crapped out on me. Anyone know a way to tell that too?
I'm using Infusion A no overclock but I am undervolting as follows:
1200Mhz -100
1000Mhz -100
600Mhz -100
400Mhz -75
200Mhz -50
100Mhz -50

[Q] Overclocking cm7 to 1600 Mhz

So overclocking cm7 to 1600 doesnt work and causes boot loops, i have been trying to get a kernel that would do it and i cant find one.
anyone know any kernels that work?

Only kernal for cm7 is the one that is with it no other kernals are compatible as for 1600 some phones run fine at 1600 others don't just depends on your CPU in your phone
Sent from my SGH-I997 using xda premium

^^^ what he said ^^^
my cappy was maginally stable @ 1300 within a very narrow voltage range. my infuse runs 100% @ 1664 with a ton of uv untill i turn on gps and everything starts to get warm. every cpu is different.
most infuses seem to be a higher test cpu than galaxy s phones though. you may be able to run at 1500 or better if you take a lot of time and figure out what the cpu likes and doesnt like. remember heat, uv and rapid voltage change can all cause instability so too much uv can cause problems as well as too little! to get maximum speed you may want keep the top few freq's at the same voltage (not the same uv but the same actual voltage) and have zero uv on the low freq's. it can be a pain to figure it all out but when you see the benchmarks you may think it was worth it.

ok well i kinda messed around with the overclocking built in and was messing with the type of governors and userspace seems to support over clocking on 1600.
really weird but my phone hasnt done the boot loop yet.
but thanks for your guy's help.

I set mine at 1600 last night via SetCPU. After 5 min it got hot and started boot looping. Its running good at 1200 now. I'm gonna bump it up little by little.
Good info, nice to know its "normal".

Honestly, the performance of CM7 outperforms all the other ROMS even running at 1.2GHz (IMO). I really don't see much of a performance increase by stepping up the clock speed, just a decrease in battery life, so it's not worth it to me.

ive talked to many people about this and most can only run at 1.4ghz even though 1.6ghz was stable in froyo. alot of people repeat "it depends on your specific chipset" but i dont buy that cop out. i think theres something wrong with the 1.6ghz setting in cm7.

pros and cons OC/UV

about time for me to change roms again. i know there are many with this option, but have never chose to pursue that option due to lack of understanding benefits. always seemed to get satisfactory battery life out of phone, but could it be better? i have noticed different speeds on my phone with different roms but is this something that can speed up and keep the smooooth in my phone?
just thought i would get some feedback of the advantages and disadvantages of overclocking and undervolting.
will it harm my infuse?
what are good settings?
what exactly would the OC or UV each do?
if i run a search on this, i know i am going to get the phone book and just figured i would get a more specific answer directly as opposed to piecing little bits together and still not being confident in what my interpretation would be.
everyone in the infuse community always seems to have the answers and dont steer the dullards such as myself in the wrong direction.
you guys are the MAN, and well, you women.....your the woman i reckon

captemo said:
will it harm my infuse?
Click to expand...
Click to collapse
No, so significant damage can be done with overclocking. Alhought if you set your ghz too high your phone might become unresponsive, overheat and/or auto reboot your device. This is normal if your on GB and some ICS roms. Don't see it much on JB becuase the some kernels dont support it. Just be sure to play with your settings and MAKE SURE SET ON BOOT IS DISABLED or else your phone will be stuck in a bootloop when overclocked beyond stable settings.
captemo said:
what are good settings?
Click to expand...
Click to collapse
I usually stick with 1400 ghz because 1600 ghz[max] drains battery too quickly for not much of performance boost and 1600 is considered unstable on most GB and ICS roms. As for CPU governor Id stick with ONDEMAND.
captemo said:
what exactly would the OC or UV each do?
Click to expand...
Click to collapse
OC is over clocking your processor to a higher ghz for better perofmance and under volting is drawing less energy

Is there like a guide saying what each CPU governor does? Because some of them are pretty confusing with their terminology, like smartassv2

Garen21 said:
Is there like a guide saying what each CPU governor does? Because some of them are pretty confusing with their terminology, like smartassv2
Click to expand...
Click to collapse
http://forum.xda-developers.com/showthread.php?t=1420742

I used to under volt a lot to get better battery life. But it seemed to make a couple apps hang now and then.
I am now on Scotts PA JellyBean ROM. Battery life is very good for me stock with this. So I have left under volt to stock settings.
Normally I'll run on smartassV2 governer. With NOOP i/o. And 100mhz - 1400mhz.. just for a little extra boost.
When I know I'll be playing a game or multitasking, I'll boost it to 1600mhz.
Overall stock settings run amazing, both battery life and performance, on Scott's PA JB and CM10.
After doing some reading, I believe I can get better results from using the above settings. It all depends on what your personal goal is.
The biggest concern you should have when overclocking is mentioned above. Boot loop, just make sure you test it for a while with set on boot un checked.
Undervolting you can go to low and also boot loop, so same applies here... leave set on boot un checked. All phones are different on what settings they run best at. Just gotta play around and see what works for you.
A good rule of thumb for under voting... go down 25mv at a time and test it out... keep going down 25mv until you get a problem or boot loop and then go back.. then you'll know your max.
You can safely under volt more on the lower frequencies than you can the higher ones. Personally I never undervolted more than 100mv across the board. And when I did, I usually kept it around -50mv.
Sent from my SGH-I997 using xda app-developers app

not for infuse but a good reference for ocuv. explains what they do
http://forum.xda-developers.com/showthread.php?t=1827635
Sent from my GT-I9300 using xda premium

This is the best guide I've found covering kernel and system tuning - CPU parameters, governors, schedulers, init.d, loadable modules, etc. It's for the SGS2 (i9000) and some of the governors/schedulers are not available on the Infuse, but much of this is applicable to our phone:
http://forum.xda-developers.com/showthread.php?t=1369817
As for OC/UV, as long as you stay away from the "Performance" governor (this runs the phone at max freq all the time), and undervolting below -75 to -100 you generally will be safe. As phones are different, it is important to test in gradual steps to ensure your phone will be reliable. Use a good CPU manager, like SetCPU, Antutu, or Voltage Control. Make sure you enable the "revert to stock" feature so that you can boot recovery and turn off any bad OC/UV. As noted above, do not check the enable on boot setting until you are certain you have a good config.
The decision to OC should take into account how you use the phone. If your phone is asleep more than 80% of the time on average, you can probably run an OC config and still have overall good battery life (i.e. lasting an entire day with nightly recharges). If you use your phone for music playback or something else that prevents it from sleeping, OC may not be for you. If you run CPU intensive games, it is better to disable UV settings while OCed.
Use CPU Spy to keep an eye on your time at each freq state (and sleep). Use the default battery stats and graph to monitor which apps are consuming the most battery. Use apps like Better Battery Stats, Android Assistant and Watchdog for more detailed monitoring of what is keeping the phone awake and which apps/processes are top cpu resource consumers. With this information you can identify problem apps and decide whether you should remove them from your phone.
From the "unintended functionality" side of the house, there are certain tweaks that will cause your phone to run at max freq ... mucking around with phone properties in build.prop can lead to runaway rild process problems (usually shows up as unusually high "Dialer" in the standard battery stats list and a phone that is warm or hot to the touch). Some of the tweak scripts in adrenaline and tbolt can cause similar problems. There is a known bug in the infuse network drivers that shows up as much higher than normal Android OS battery usage. This can usually be corrected (short term fix) by toggling Flight/Airplane mode off/on. Running the stock UCLB3 GB kernel also seems to minimize this issue (assuming you are running a GB ROM), but flash with caution as you will need to disable voodoo lagfix first. (You will also lose CWM recovery, OC/UV capability, and be on the slower stock file system setup).

I have done a fair amount of experimenting including lots of time on conservative governor with Fmax=1600 and never had any problem that I attributed to OC'ing.
In contrast I did find a limit on UVing. I just updated my thread with my experience on uv here:
http://forum.xda-developers.com/showthread.php?p=32552571#post32552571
The bottom line is that for MY phone, the following works fine:
100 Mhz: 950mv max – 50mv = 900 millivolts
200 Mhz: 950mv max – 25= 925 millivolts
400 Mhz: 1050mv max – 50mv = 1000 millivolts
800 Mhz: 1200mv max – 75 mv = 1125 millivolts
1200 Mhz: 1275mv max – 50mv = 1225 millivolts
1600 Mhz: 1400mv max – 75mv = 1325 millivolts
Some other links with others' experience suggestions about UV'ing for Infuse:
Hozw low is your undervolt?
http://forum.xda-developers.com/showthread.php?t=1693689&highlight=kernel
[Q] Recommended SetCPU settings?
http://forum.xda-developers.com/showthread.php?t=1292836&highlight=setcpu
You’ll note the last thread has comments from Entropy’s settings.
Also Zen and qkster gave advice in the first thread (my thread).
All three guys very well respected and worth listening to.
Entropy mentioned you can uv the higher frequencies more than the lower (different than what was posted earlier in this thread). I don’t know for sure but I’d lean toward Entropy’s advice on that matter.
I think all in all somewhere between 50 and 100 is the max you can expect to undervolt.
What can be achieved varies with phone as stated by many.
You are welcome to experiment with slowly decreasing. That's what I did.
But in the benefit of hindsight, the process of slowly decreasing is tedious. And going beyond the limit was a little scarey for me. Could've been worse if the phone crapped out at a critical time during "experimenting". Like almost everything related to battery life, the results (how much benefit) seem y subjective (difficult to measure quantitatively). Most people say they don’t notice a dramatic difference with UV. If you want to get the low hanging fruit without a lot effort, you might just try 50 down. That's what I'd do if I had to do it all over again.
By the way, setcpu can be set up to provide a failsafe escape route even if you go overboard. There is a zip file that will toggle the setcpu settings off when launched from CWM. You just have to put the zip file on your sd card before you start tweaking. See "safe mode" in the setcpu documentation.

started to wonder at first whether i would get any responses after 218 views and nothing, but i knew the community would come through as they always do. all the regulars as usual regulars ( Zen, Quickster and others) are always eager to help. i think you have all provided me with the valuable info i requested.
thank you much party people