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iRun26.2
Feb 13, 2011, 08:01 PM
I love the thought of squeezing even more battery life out of my 11.6" MBA (although it really is pretty good already), but operating the CPU at a lower than designed voltage seems a little risky.

Has anyone had any problems using it with the 11.6" MBA? What can happen? Can you screw up your system (compromise the integrity of your data) if the lower voltage causes your CPU to hiccup?

(Maybe, as an engineer, I worry more than most because this is something that goes against good design practices)



gimmi80
Feb 13, 2011, 08:24 PM
I love the thought of squeezing even more battery life out of my 11.6" MBA (although it really is pretty good already), but operating the CPU at a lower than designed voltage seems a little risky.

Has anyone had any problems using it with the 11.6" MBA? What can happen? Can you screw up your system (compromise the integrity of your data) if the lower voltage causes your CPU to hiccup?

(Maybe, as an engineer, I worry more than most because this is something that goes against good design practices)

I've coolbook since a couple of weeks. I run my 1.6ghz core 2 duo at 0.875v
I would like to go lower (0.85v) but the software does not allow it and I'm not too familiar with terminal (apparently it can be done from there).

In this forum multiple user have coolbook installed and active and no problems have been reported yet.

entatlrg
Feb 13, 2011, 08:41 PM
I have the same question as iRun plus I'm concerned about turning the fan speed down, although I could do without the roar from my 13" MBA ... my 11" doesn't get loud at all.

iRun26.2
Feb 13, 2011, 08:48 PM
I have the same question as iRun plus I'm concerned about turning the fan speed down, although I could do without the roar from my 13" MBA ... my 11" doesn't get loud at all.

Does Coolbook let you control the fan too (or does that require additional software)?

Additionally: You bring up an often not mentioned advantage of the 11.6" vs the 13.3" MBA: Quieter (and cooler....I like both!) I think I will be biased towards getting ULV processors in the future.

bshaf1
Feb 13, 2011, 08:52 PM
the worst case scenario from what i've read is that your computer starts having kernel panics if it's undervolted..

..increase the voltage and then you should be good

iRun26.2
Feb 13, 2011, 09:24 PM
the worst case scenario from what i've read is that your computer starts having kernel panics if it's undervolted..

..increase the voltage and then you should be good

Will you lose all of your unsaved data when you get a kernel panic?
(Is that like the 'blue screen of death' in MS Vista?)

jrabbit
Feb 13, 2011, 09:56 PM
Will you lose all of your unsaved data when you get a kernel panic?
(Is that like the 'blue screen of death' in MS Vista?)

Yes.

Does Coolbook let you control the fan too (or does that require additional software)?

No, you need separate software.

Note that you don't really want to limit the fan speed (if you do, and screw it up, you can cook your system). The reason to run fan control software is to change the default thresholds. Most people can increase the default fan speed a bit without noticing a change in sound level. This results in keeping the CPU cooler longer: it takes more fan noise to cool down a hot CPU than it does to keep it cool in the first place.

I posted this a while back...

Each CPU core behaves in a unique way; the factory defaults are set with fairly generous tolerances. The key to using CoolBook effectively is:
Find the "magic" pairs: a. Lowest voltage for highest frequency the chip supports; b. Highest frequency for the lowest voltage the chip supports
Once you find the "magic" pairs, you can set a number of "in between" voltage/frequency pairs

Keep in mind that heat (power) is generated linearly with the frequency and with the square of the voltage, so that's why managing both is important; that's also why focusing on voltage is key. The formula is P = C x V^2 x F (Power/Capacitance/Voltage/Frequency).

For my system, this is what I found/use:

CoolBook settings:

MBA 1.8GHz 128GB SSD

Adapter:
800MHz 0.9000V
1200MHz 0.9000V
1400MHz 0.9000V
1600MHz 0.9000V
1800MHz 0.9625V

Battery:
600MHz 0.9000V
800MHz 0.9000V
1200MHz 0.9000V
1600MHz 0.9000V
1800MHz 0.9625V

Throttling level: High
Thermal limit: 85C

"Base" Pairs (found by testing):
1600MHz 0.9000V [highest frequency for lowest voltage]
1800MHz 0.9625V [lowest voltage for highest frequency]

I then set smcFanControl to keep the minimum fan speed at 1800rpm when on battery, and 3200rpm on A/C. Those exceed the default minimum speeds, but it's far easier for the system to stay cool than to get hot and cool back down. I chose those speeds because they are just barely audible (to me; your ears may be better or worse).

gimmi80
Feb 13, 2011, 10:12 PM
I posted this a while back...

You keep fairly high voltage for your processor.
I've a 1.6GHz and it runs on 0.875v at all speed

I keep:
A/C
1200 MHz 0.875v
1400 MHz 0.875v
1600 MHz 0.875v

Battery
600MHz 0.875v
1600 MHz 0.875v

Throttling Medium

gimmi80
Feb 13, 2011, 10:28 PM
I've actually looked around and it seems that keeping the settings too low might worsen battery life.
I'm confused.:confused:

aleni
Feb 14, 2011, 02:31 AM
i use coolbook on my 1.4Ghz 11" air, i can get 6.5-7 hours of daily usage with that.

the setting for all clocks is 0.875v

jrabbit
Feb 14, 2011, 06:53 AM
You keep fairly high voltage for your processor.
I've a 1.6GHz and it runs on 0.875v at all speed

I keep:
A/C
1200 MHz 0.875v
1400 MHz 0.875v
1600 MHz 0.875v

Battery
600MHz 0.875v
1600 MHz 0.875v

Throttling Medium

I don't really have a choice on the voltages... I tested everything, and what I posted is the best the CPU in my MBA will do reliably; the tests generate kernel panics with lower voltages at the higher frequencies. You must have gotten luckier than me in the CPU lottery!

omniatlas
Feb 14, 2011, 07:04 AM
I don't really have a choice on the voltages... I tested everything, and what I posted is the best the CPU in my MBA will do reliably; the tests generate kernel panics with lower voltages at the higher frequencies. You must have gotten luckier than me in the CPU lottery!

Perhaps the 1.6 ghz processors are more stable than the 1.8?

I've been reading - the macbook air 1.6 doesn't seem to have problem reducing the voltage to 0.875

Just found a good writeup of the program -- http://gigaom.com/apple/fix-macbook-air-streaming-video-and-overheating-problems/

I might take the gamble and spend the $10.0.

DarwinOSX
Feb 14, 2011, 07:57 AM
Its risky. Don't do it.

gimmi80
Feb 14, 2011, 08:42 AM
I don't really have a choice on the voltages... I tested everything, and what I posted is the best the CPU in my MBA will do reliably; the tests generate kernel panics with lower voltages at the higher frequencies. You must have gotten luckier than me in the CPU lottery!

In another thread of this forum I found several MBA 13' user that have similar settings...The most preforming processor might be more demanding... who knows?

Anyway my question remains the same, both you and the girl in the link posted above (Jenny Kortina) use many setting at high throttling.
I use two settings only at low throttling (at least in battery power mode).

My rationale was that when I don't need power I want to use the processor at the lowest frequency available and, when I need more power, switch to the highest setting.

This, of course, changes based on the type of workload that is done on the MBA, but in my case I mostly use the MBA as sort of typing machine (requiring low performance). Sometimes I use Aperture and the processor bumps up to 1600MHz and stays there all the time.

I don't know... I need more feedback

gimmi80
Feb 14, 2011, 08:44 AM
I don't really have a choice on the voltages... I tested everything, and what I posted is the best the CPU in my MBA will do reliably; the tests generate kernel panics with lower voltages at the higher frequencies. You must have gotten luckier than me in the CPU lottery!

By the way, if you are talking about the MBA that is in your signature, the rev A model, that's a complete different animal, therefore our settings are not comparable.

Even the new 1.8GHz processor is different compared to the rev A.

Your settings are inline with the one that other rev A user adopted.

kryca
Feb 14, 2011, 09:08 AM
Its risky. Don't do it.

It isn't risky. Do it. Unless you give some concrete evidence besides the ubiquitous "Apple knows best what is good for you".

The $10 are the best I spent on the MBA.

aleni
Feb 14, 2011, 09:30 AM
You keep fairly high voltage for your processor.
I've a 1.6GHz and it runs on 0.875v at all speed

I keep:
A/C
1200 MHz 0.875v
1400 MHz 0.875v
1600 MHz 0.875v

Battery
600MHz 0.875v
1600 MHz 0.875v

Throttling Medium

why did u remove the 1.2 and 1.4ghz settings? removing those clocks will result in decrease battery life, when you are doing some task that needs only 1.2 ghz, it will run in 1.6ghz thus decreasing battery life.

gimmi80
Feb 14, 2011, 09:56 AM
why did u remove the 1.2 and 1.4ghz settings? removing those clocks will result in decrease battery life, when you are doing some task that needs only 1.2 ghz, it will run in 1.6ghz thus decreasing battery life.

I followed the recommendation of somebody on this forum.
The rationale is to have the CPU work at 600MHz most of the time and bump up to 1600MHz only when needed.

I've heard the argue that forcing the CPU to work on low frequency (600MHz) when it actually needs more power, could achieve the opposite effect (I mean use more battery).

Mac32
Feb 14, 2011, 10:14 AM
OK. Quick answer:
I've used Coolbook for several years on several macs, no problems. With Coolbookcontroller your CPU will live longer if anything (less heat).
Use the lowest volt settings on all the stock CPU frequencies. Don't change the stock CPU frequencies (Don't use 600mhz, too slow!). Also, use "high" throttle.

If you get kernel panicks, just use a higher voltage setting, - but *by far* most likely your MBA 11.6 will work flawlessly.

impulse462
Feb 14, 2011, 11:26 AM
Its risky. Don't do it.
It's only risky for people who don't know any better.

Instead of just doing what apple thinks is best for you, you could think, "hey, lowering the voltage for anything means less heat and less power,"

The worst that could come out of lower voltages is you'll get a kernel panic. You boot up again and revert to the older voltage.

Raising the voltage to overclock a cpu is the risky business.

2IS
Feb 14, 2011, 01:26 PM
Its risky. Don't do it.

And you're basing this off what? If you're going to make a claim, at least back it up with something.

Back on topic:

Coolbook does not adjust fan speed, and as mentioned previously, you don't want to. However, one of the benefits of coolbook is that lower fan speed is an automatic byproduct of using it. Lowering the CPU voltage serves multiple purposes.

1) It gives you greater battery life, particularly under load situations.
2) CPU runs cooler due to lower voltage and due to this reason, the fan rarely if ever ramps up to its full speed simple because it doesn't need to.

The down side is that if you go to low or if you have a CPU that just isn't as good as some other ones, you may get instability. Just start off with small steps, meaning, don't just pick .875v across the board. Just because it worked for someone else doesn't necessarily mean it will work for you. I'd start by pushing a bit more voltage than that for the higher frequencies and just go from there.

drxcm
Feb 14, 2011, 02:04 PM
My experience with the 1.6 is very positive.
Lowest voltage for all clock speeds, no kernel panics under heavy load.
Also I'm getting around an extra hour of battery life under normal loads / usage (around 6 hours).

Those that say it is risky clearly haven't tried it, or don't know what they are talking about.

gimmi80
Feb 14, 2011, 04:59 PM
OK. Quick answer:
I've used Coolbook for several years on several macs, no problems. With Coolbookcontroller your CPU will live longer if anything (less heat).
Use the lowest volt settings on all the stock CPU frequencies. Don't change the stock CPU frequencies (Don't use 600mhz, too slow!). Also, use "high" throttle.

If you get kernel panicks, just use a higher voltage setting, - but *by far* most likely your MBA 11.6 will work flawlessly.

Thanks. I'll follow your recommendation.

iRun26.2
Feb 14, 2011, 09:32 PM
My experience with the 1.6 is very positive.
Lowest voltage for all clock speeds, no kernel panics under heavy load.
Also I'm getting around an extra hour of battery life under normal loads / usage (around 6 hours).

Those that say it is risky clearly haven't tried it, or don't know what they are talking about.

You have convinced me! I think that I am going to buy it and try it (though it kind of goes against my engineering intuition).

It makes sense, though, that that the 1.6MHz machine would be better at dealing with lower voltages that the 13.3" model chips. The ULV chips were probably picked out as being 'special' in that they worked better at lower voltages while the other chips did not. I suspect that the chips really aren't physically any different: they just passed tests that the other chips did not (hence the higher price from Intel).

(Sort of like normal ICs that are rated for either Commercial, Industrial, or Military temperature ranges with Military temperature versions costing the most)

omniatlas
Feb 14, 2011, 11:09 PM
I bought it -- currently underclocked all cpu frequencies to 0.875. Will post my battery lifespan when I'm done playing with it -- anyone know if B/2 should be checked? It halves the bus speed.

Mac32
Feb 15, 2011, 03:03 AM
Dont use B/2 - that's when the battery actually might drain faster with coolbook AFAIK. The bus speed of the 11.6 is already slower than the 13MBA anyway.. And 1.6ghz will use more battery (and create more heat) than 1.2ghz even if the volt is the same - so again, my advice is to stick with the original CPU freqs.

omniatlas
Feb 15, 2011, 03:41 AM
Okay thanks -- I have the frequencies

800, 1200, 1400 and 1600 all setup with 0.8750 V.

Right now i've used the laptop for about 3.5 hours, with some music playing, youtube videos, and web browsing. LCD brightness is set to 50%. Have about 39% left, so lets see how much longer I can stretch this.

iRun26.2
Feb 15, 2011, 06:46 AM
Dont use B/2 - that's when the battery actually might drain faster with coolbook AFAIK. The bus speed of the 11.6 is already slower than the 13MBA anyway.. And 1.6ghz will use more battery (and create more heat) than 1.2ghz even if the volt is the same - so again, my advice is to stick with the original CPU freqs.

To me, it seems like there is a lot of 'quess work' associated with using Coolbook. It seems like there ought to be some way to estimate what settings are most appropriate for the type of work one is doing.

For example, logically more power is used (and more heat is generated) when running at 1.6GHz than 1.2Ghz. However, that doesn't necessarily mean you would always use 1.2GHz since at 1.6GHz you get your computations done sooner and more quickly enter an even lower power mode.

I wish there were recommendation as to what settings would be suggested for various scenarios. In my mind, halving the bus speed doesn't seem like it would ever make make sence since your CPU would be likely running at full speed just waiting for data. But is this thinking logical?

omniatlas
Feb 16, 2011, 05:14 AM
I got about approximate 6 hour with coolbook on my 11". I'll try and do more 'scientific' testing by running itunes from 100% batter and see how long it lasts then.

Please post your stats.

Mac32
Feb 16, 2011, 07:04 AM
To me, it seems like there is a lot of 'quess work' associated with using Coolbook. It seems like there ought to be some way to estimate what settings are most appropriate for the type of work one is doing.


Not really.. It's quite obvious. Just try it out yourself. If you put 1.6ghz as the only CPU freq, you will soon find out that the standard temp on your MBA will become noticably higher.

MacRumorUser
Feb 16, 2011, 07:13 AM
I got about approximate 6 hour with coolbook on my 11". I'll try and do more 'scientific' testing by running itunes from 100% batter and see how long it lasts then.

Please post your stats.


Yeah but I've managed to get just over that without any coolbook running, with just browsing websites (without flash) and writing & checking email. Screen 1/3rd brightness.

So (genuine question) wondering what were you doing anything dramatically different with your machine with coolbook on to say it made a difference ? :confused:

2IS
Feb 16, 2011, 11:16 AM
Yeah but I've managed to get just over that without any coolbook running, with just browsing websites (without flash) and writing & checking email. Screen 1/3rd brightness.

So (genuine question) wondering what were you doing anything dramatically different with your machine with coolbook on to say it made a difference ? :confused:

Coolbook does not do anything when your computer is in an idle or nearly idle state. The lowest frequency/voltage setting in coolbook is not any lower then what the processor runs at by default. So if you get 7 hours doing virtually nothing, you'll get the same 7 hours with coolbook. Under load situations however, coolbook keeps the lower voltage delivery as the clock speed increases so your runtime is not as adversely affected.

I have not done a controlled test with and without cool book to get exact figures, i just don't have the desire to go through two battery cycles to get solid figures. What I can tell you is that my usage patters with coolbook are the same as before I got it, and the laptop runs noticably cooler and I have yet to hear the fan crank up to full speed with coolbook running, something that it did fairly frequently prior to coolbook.

FFabian
Feb 23, 2011, 06:51 PM
Is there a broad consent on which settings are stable for all/most Air 11" 1,6?

I'd like to know the settings I can use without doing hours of testing with CPUtest - or is testing always recommended?

topmounter
Feb 23, 2011, 07:10 PM
Ideally you would run any CPU at the minimum stable voltage for that particular CPU. Apple juices the voltage up because there are variances across different batches of CPU's and they don't want to have to test every batch or even each CPU for its optimum stable voltage.

The only risk you run is that of a kernel panic, but that is why you test to find a stable voltage before you start writing your doctoral thesis.

Psilocybin
Feb 23, 2011, 07:38 PM
i just started using coolbook and i add smcfancontrol for gaming and movies
great experience, coolbook is well worth the $10

aleni
Feb 23, 2011, 08:30 PM
Is there a broad consent on which settings are stable for all/most Air 11" 1,6?

I'd like to know the settings I can use without doing hours of testing with CPUtest - or is testing always recommended?

i use 0.875v for all the settings with 11" (1.4ghz), it works OK. but you have to test it yourself for the 1.6ghz clock setting.

anyway, my boot time is increased by 12 seconds after using Coolbook, and it's not as snappy as with stock voltage settings. guess i will uninstall coolbook because of this.

iRun26.2
Feb 23, 2011, 09:04 PM
i use 0.875v for all the settings with 11" (1.4ghz), it works OK. but you have to test it yourself for the 1.6ghz clock setting.

anyway, my boot time is increased by 12 seconds after using Coolbook, and it's not as snappy as with stock voltage settings. guess i will uninstall coolbook because of this.

I disabled Coolbook on my 11.6" machine so that I could reduce my boot times. I'm thinking I am going to try it out again, though.

There are a lot of people who really like Coolbook and it sounds like they use it regularly. It doesn't make sense that it should slow your machine down (since really all you are doing is lowering the voltage levels...and lowering the voltage shouldn't affect performance just power used: CPU power should be proportional to the square of the voltage for any given frequency)

aleni
Feb 23, 2011, 09:28 PM
I disabled Coolbook on my 11.6" machine so that I could reduce my boot times. I'm thinking I am going to try it out again, though.

There are a lot of people who really like Coolbook and it sounds like they use it regularly. It doesn't make sense that it should slow your machine down (since really all you are doing is lowering the voltage levels...and lowering the voltage shouldn't affect performance just power used: CPU power should be proportional to the square of the voltage for any given frequency)

but when the first time i used coolbook, my boot time was the same as new. about 2 months later, i noticed it's increased. maybe it's not coolbook's fault at all. maybe after u installed lots of apps, the boot time will be decreased.

iRun26.2
Feb 23, 2011, 09:33 PM
but when the first time i used coolbook, my boot time was the same as new. about 2 months later, i noticed it's increased. maybe it's not coolbook's fault at all. maybe after u installed lots of apps, the boot time will be decreased.

Try disabling it and see if that makes a difference.

aleni
Feb 25, 2011, 10:10 AM
Try disabling it and see if that makes a difference.

yes it does, i disabled coolbook, then my boot time is back again like normal, about 14-16 secs.