overclocking,,it is dangerous??
 

guys.. it is dangerous to our n900 that we always turn to overclock?? because some patch here was set to overclock.. just a question..

Re: overclocking,,it is dangerous??
 

sure is, it might blow up and kill everyone within a 10 mile radius!

BEWARE!

Re: overclocking,,it is dangerous??
 

Most likely no negative effects. Just don't use it overclocked on a packed bus, just to be on the safe side :P

Re: overclocking,,it is dangerous??
 

Lol what are you overclocking? :D a phone a PC or a nuclear guided missile with an arm chip used for running the guidance device?

Re: overclocking,,it is dangerous??
 

Yes it is, but only for your phone.
You can frie your processor, or not =)
Depends on how you do it, and depends on your phone too.
See my case, i never had a problem with overclock (not mentioning crashes and freezes, but it doesnt happen everytime).
Newer Power Kernels are very stable and crashes decreased significantly (bit this is MY case).
Some phones never run well with overclock, other ones even stock...
My phone is overclocked almost since i have it (about 1,5 year ago) and today it´s better than ever, with CPU Speed and Battery tweaks.
By default, it starts with 805Mhz, but when i want more, is too easy to change to 1000Mhz for a while.
So, i say you can try overclock, but pay attention on the tutorials and read carefully. Make each procedure as it says. And at every different behavior you notice, let the community know.
But, it is YOUR resposability. Do if you want to.

=)

Re: overclocking,,it is dangerous??
 

sir what on the safe side???

Re: overclocking,,it is dangerous??
 

sir what on the safe side??? someone says it not safe when you overclocked when not in use but in battery patch it sleep when idle..

Re: overclocking,,it is dangerous??
 

Was meant to be a joke. Anyway N900 has by default 2 frequencies one minimum(125 MHz) and one maximum(600 MHz). When idle it would automatically take minimum and when it is in use it will jump up and down between minimum and maximum on demand. By changing the maximum from 600 to a higher value the minimum(idle) value doesn't have to change(though some people prefer it also higher so that device is more responsive in an event of something like a phone call). I don't use battery patch so I don't know what effect overclocking would cause there, but if the author of the patch stated that overclocking may cause problem when N900 is idle it would be wise of you to leave the min frequency alone. You should probably ask in the respected thread about the effects and also ask about changing voltage profiles(ulv, xlv, lv) normally you'd opt for the lowest that is stable on your device, but then again you should ask that on the other thread.

Re: overclocking,,it is dangerous??
 

You can't fry your CPU in the N900 even if you overclock. Well, you will probably be the first in the world maybe if it happens. This is because most modern CPUs have safety features built in. N900 will also freeze up and stop responding well before the CPU goes into some kind of melt down temperature etc. As long as you don't over-volt the CPU, it is pretty much impossible to physically damage your N900 no matter what you do in relation to frequency limit changing. The custom kernel for the N900 provides the option to under-volt but not over-volt anyways. So you are safe there. =P

Anyways, if I had to answer your question now...
No, it's not dangerous to overclock the N900.

Also, power kernel has many security measures to ensure that it is.
(e.g. It loads default value upon an unexpected "non-clean" reboot)

Re: overclocking,,it is dangerous??
 

I have been using qCPUfreq for 2 months now in combination with kernel power48 and i keep the frequency at a permanent 900 MHz, although the device switches back to 250 MHz for most tasks (90% of the time). I had no strange reboots/freezes after intensive use for 10 days

Re: overclocking,,it is dangerous??
 

Some Components of the N900 will lose much of their estimated Lifetime through overclocking. Everything gets hotter. This may not be the case if you overclock & undervolt at maximum efficiency. Maybe.

But anyway, the components loosing lifetime through overclocking still wont be the first to die, probably. Except for the Battery. Batteries dont like running hot and stuff.

Re: overclocking,,it is dangerous??
 

Please don't say overclocking is safe. Just because your cpu still works doesn't mean OP is as lucky.
http://talk.maemo.org/showthread.php?t=68795
http://talk.maemo.org/showthread.php?t=71107

Re: overclocking,,it is dangerous??
 

Running CPU @ 500MHz it lasts 100.000h, @ 600MHz it lasts ~20.000h (at nominal temperature!!) - that's why 600MHz sometimes is called "official OC".

Running CPU @800MHz may mean it gets permanently irrecoverably fried after as little as 2000h total of actually running at that clock speed (see my prev posters about dynamic clock speed and idle)

Generally OC is *strongly deprecated* unless you definitely know what's the deal - most posters before exposed a scary ignorance regarding that, stating only FUD and handwaving on a level of "WFM so it's safe"

Nokia definitely did invest lots of work to tune the device to run as fast as safely possible, while still ensuring a reasonable product lifespan. No smartass can outperform this on a "no clue why but it works" basis.

regards
Joerg (EE)

Re: overclocking,,it is dangerous??
 

@joerg_rw - what is missing in your equation is voltage. So if you undervolt while overclock, thus keeping total energy (i.e. average power multiplied by time) in sane limits (near stock) you are safe. And your explanation may leave someone with the impression that overclocking at 800MHz means locking CPU at that speed - which you perfectly know is not true.

Re great Nokia job - recently i have played a lot with kernel code in both n900 and n950, and TBH I am under impression that Nokia just copy/cat what comes from TI. And what comes from TI is a set of parameters which are safe for TI evaluation boards, thus no clock/voltage optimizations specific to n900 exists in n900 kernel. What I totally agree on is that the job Nokia HW engineers have done to dissipate the heat from the SOC is absolutely great.

Re: overclocking,,it is dangerous??
 

sorry I have to disagree, for two reasons: first your equation is missing the true nature of the problem which is electromigration and not voltage or power or energy. And second it's missing SmartReflex(R) set of measures in OMAP, which mostly defeats the only possible purpose of your undervolting which was to reduce current density, the true cause of electromigration. Higher clock rates cause steeper edges in level changes, cause faster charging of parasitary capacitors, cause higher current density surges, cause more electromigration.
Actually SmartReflex function blocks inside OMAP, which are taking care about virtually every single gate and transistor and adjust their individual working points (basically the quiescent current) accordingly to match the clock frequency might even cause your undervolting to result in a worse situation regarding electromigration. I for sure don't know enough of the particular details of what's going on inside the chip's gates to rule it out. If you actually know more... I'm listening.
So no, you're NOT safe.

Please don't first turn my words into their opposite to accuse me being a liar then! :-( What of >>2000h total of actually running at that clock speed (see my prev posters about dynamic clock speed and idle)<< makes you think I told something about CPU being permanently locked at max clockspeed?

Sure the parameters come from TI, as not even Nokia can afford the needed tests or had the mandatory insight in and knowledge about the chip's internals, nor the tools like electron microscopes etc to examine chips suffering EM after test runs. It's however a weird idea to think of those parameters as "optimized for TI eval-boards". And it's silly to think you could optimize those for N900, as it's just the chip and only the chip that's relevant here and that is determining those parameters. Any design particulars like heat dissipation of N900 are absolutely irrelevant for that, they only where relevant if the main problem of OC was overheating which it definitely is not.
All this shows again why there's so much nonsense around OC, everybody is starting with arbitrary random assumptions (like OC problem was heat) and then gets involved in sophistic developments and theories based on those false assumptions (here e.g. undervolting, maybe even dynamic, based on ambient temperature, eh?)

Sorry if the above maybe sounds a bit harsh, but it really annoys me since almost 2 years now, and all the info has been given over and over and over again, it's all there for everybody to read and understand. But no, OC is cool, and WFM, and of course every EE that tells something different is just a fool, no matter if it's Igor of Nokia, or me, or the guy writing the OMAP3430 datasheet. N900 community is so smart they know best, no doubt.

cheers
jOERG

Re: overclocking,,it is dangerous??
 

Have been running mine on 850mhz for the last 18months and have widgets set up to jump to 1000mhz for emu's when I wish.

I have seen no ill effect at all.

Re: overclocking,,it is dangerous??
 

*SIGH*
Didn't you get it that all that info of yours is mere rubbish, as long as you can't tell how many hours your CPU ACTUALLY SPENT IN 850Mhz, and how many hours in 1000MHz?
It's exactly that type of statement that makes everybody fail to understand what OC is *really* all about. The deal is NOT "18 months with no issues".

But don't worry, Texas Instruments has already evaluated those values that really matter:
100kh@500MHz
23kh@600MHz
will result in no more than 50 of 1000 CPUs dead after that time.
For the normal CPU, the MIL CPU is a *bit* worse:
50kh@500MHz
10kh@600MHz will result in 70 of 1000 dead

you know what's an exponential graph? look at 50@500, 10@600, and tell me what you guess will be a reasonable value to expect for lifespan at 800!
Your CPU won't age when device is sitting there idle for 18 months, it *will* during you watching youtube videos though.
http://mg.pov.lt/maemo-irclog/%23mae...03-11T03:04:11


/j

Re: overclocking,,it is dangerous??
 

so it is dangerous sir?

Re: overclocking,,it is dangerous??
 

yes, exactly like smoking is dangerous to your health and reduces your statistic lifespan.
Just with smoking you can stop and 3 or 4 years later your statistic lifespan is back to average of non-smokers.
Stopping OC won't heal the CPU fro EM damage done during OC. And OC to 1000MHz is more like smoking crack than like smoking cigarettes.

/j

Re: overclocking,,it is dangerous??
 

i am using batterypatch and changing the default as default but on idle i think its underclock...

Re: overclocking,,it is dangerous??
 

@joerg_rw
wow! information overload! i like it! thanks for sharing. :)

Re: overclocking,,it is dangerous??
 

if the smoking analogy didn't help, think about an incandescent bulb built to last 10.000h @ 110V. You can operate it at 140V, even at 220V. And of course it doesn't matter much as long as you switch it on only 5s a day. But it's all up to your usage pattern, your kids/software (and the mistakes they commit that might leave the light on errr the CPU at 100% load and thus at max clock without you even noticing), and your luck with this particular bulb how long it lasts (in NY there's a bulb in a fire house that shines since some 100 years and never gets switched off or needed any replacement, maybe your particular CPU is the same miracle)
One thing's for sure: at doubled load neither the bulb nor the CPU will live for even 50% of their regular active lifespan, it's more like each 10% increase in clock speed halve the expected lifespan.
Let's do the math:
500 + 2*10% =~600; 50.000 / 2 / 2 = 12.500 (datasheet says 10.000)
600 + 3*10% =~800 10.000 / 2 / 2 / 2 = 1250h
800 + 2*10% =~1000 1250 / 2 / 2 =~300h

I'm actually suspecting the real figures are worse

/j

Re: overclocking,,it is dangerous??
 

thanks a lot sir joerg

Re: overclocking,,it is dangerous??
 

Of course it is electromigration which is the main problem we are discussing, did I say something else? But EM does not appear out of the nowhere, it has it's physical explanation, more on that later on.

Sure, I am not aware which exactly technology was used to produce 3430 SoC. But that does not render laws of physics invalid.

How did you come to a conclusion that higher clock rates lead to steeper edges?!? Is there something in datasheet about that? I failed to find such a thing, will you point it for me. I really wonder how you came to that, perfectly knowing it is a square waveform (in core), not sine or triangle. Yes, it is not a pefect square, and this square is derived from sine, but the only places where it is sine are quartzs(or whatever clock generator is used and which run at relatively low frequencies) and PLLs. By raising frequency (i.e. switching more often) we do not affect clock pulse edges , it is duration and period which is affected. So we are not charging/discharging gate parasitic capacitor more quickly, just more often. And this capacitance is related to voltage, because of the structure of the MOSFET, i.e. the higher the voltage, the bigger capacitance we have when transistor source-drain channel is closed. Of course it is not linear and is highly dependable on physical structure of the transistor, but still the effect remains. That is one of the reasons why lowering the voltage reduces EM (because of reduced gate capacitance, thus reduced transient current needed to switch the CMOS). The other reason why reducing voltage leads to reduced EM comes from transient function of RC serial cirquit:

i(t)=(V0/R)*e^(-t/RC)

so, the less voltage (i.e. charge) in the start of the transition we have, the less initial current is (and so is the current density).

And I have never said that SmartReflex shoud be turned on while oveclocking. I don't believe it can do better than manually ajusting OPPs for each particular chip.

Sorry if you understand me like that, I was just saying that someone without technical background MAY misunderstand you. Didn't want to be offensive.

No, it is not only the chip, you are EE, you should know that. It is the stability/noise on power lines, it is the PCB material used, it is the shielding, etc. The fact that AFAIK all of the n900s work reliably at 600 MHz when supplied with a voltage 30%-40% lower than stock means that somewhere someone did't do their homework. And the fact that SmartReflex was disabled in PR1.2 (not sure for PR13) supports my conclusion that SoC in n900 is far more capable, it is just SW team responsible for frequency/voltage management did't do the best they can.

And you can look at Harmattan DSP bridge driver for more proves. If I read the code correctly, the driver does not allow 3630 DSP to go above 600 MHz. Which is funny, because it is capable of going up to 870MHz

And overheating is not a problem in n900 because of the thermal dissipation design of PCB/case. If it wasn't so good then OC to almost double of what is stated to be overdrive frequency (600 MHz) would be impossible, thus my point.

I am assuming that your statement that heat dissipation is unrelated to EM and OC is caused by a lack of coffee. Two players in EM are (search for Black's equation for more info):

1. current density
2. junction temperature

Curent density is major player here, but this does not mean that temperature could be ignored. I don't want to go into details here of the physics behind EM, but in simple:

electromigration is a process of moving metal atoms caused by electrons stricking those atoms. It appears at junction between metal wires and semiconductor. Really simple explanation, but there is enough info on internet if someone wants to read more.

So how is the temperature related to EM? The answer is - the higher the temperature the bigger is the amplitude of the atoms in crystal lattice, the higher is the probability an electron (or groups of electrons, one is not enough) to strike with enough energy to move the atom to a different place. So with lowering the junction temperature we are reducing the EM effect. The junction temperature is tightly related to termal resistance inside the silicon, and thermal resistance between SoC and PCB. So with a good thermal desing (which seems to be the case with n900) you are lowering junction's temperature and reducing EM.

I have absolutely no problem with how you express yourself, it is your way of explaining things :)

Re: overclocking,,it is dangerous??
 

If we talk probability here and assuming that people "generally" don't use their "high-end" (which even N900 was at the time) smart phone for longer than 4+ years these days... It is more safe than dangerous to overclock within the boundaries of what the Kernel Power on the N900 allows. This is known fact. If it isn't a known fact, many, I mean MANY people here would have had their N900 die, crash, burn and explode on their faces. You also cannot deny that majority of people are much more willing to say what is bad than what is good when it comes to their experiences. So to me, overclocking the N900 is safe no matter what the nay sayers say.

"Safe" is a very vague term by the way. There is always a risk in everything. Even just turning on your N900 is reducing its life span. Some CPUs in the N900 also have higher yield than others. So on some samples, running it at 1000MHz might actually put about the same stress as another N900 running at a stock max 600MHz. Some at 600MHz might even be more stressed and have shorter life span than some "overclocked" to 1000MHz. But both could have a life span of over 5 years or just 5 months. We just don't know. What we do know is that more people than not have no issues "so far" with overclocking up to their "stable" limits. This is fact like it or not. So for now, I'm saying it's safe. How safe? That is up to pure luck.

Re: overclocking,,it is dangerous??
 

Going by the given hours for each frequency it can be concluded that overclocking will have the same effect in normal use.

Let's say 600MHz gives a lifetime of 20000h, while 800MHz gives 10000h. All this chips are running on demand clocks unless tinkered with. When overclocking the N900 we are definitely lowering the voltage at 800MHz compared to stock since apparently all N900s are capable of such feat. This most certainly has an impact on ultimate lifetime (positive).

Here is my experiment:

600MHz takes 7s to compute a task and go to rest
800MHz takes 4s to compute a task and go to rest

Going purely on this and not considering lower voltages, lifetime during normal use equals out.

Also, let's not forget, TI produced A8 running at 800MHz under the 3440, optimized for performance. Do you really think, it's a completely different SoC as opposed to 3430? I doubt 800MHz clock has such a dramatic impact as stated by TI. They surely wanted to sell the 3440.

It's a simple logic, there is no need to get into so many details like freemangordon to prove a point, even though I appreciate it a lot and had a flashback of being in my physics class :)

Re: overclocking,,it is dangerous??
 

@jakiman: err, sorry - how are you able to make statements of 4 year stability of a device that's available since less than 2 years? I'm not inclined to do a per-sentence reply here but let me say your whole conclusion chain once more is an example of "based on false assumptions" - you CAN NOT state something is safe based on a limited-duration random field test where you don't have control about *any* of the critical parameters like usage patterns, hell not even about feedback for problems.
Your arguments are like "sure this car's engine will last >1000 miles at full speed, as we've seen no defects here at the 250 miles checkpoint yet" - does this sound honest or reassuring?
What you *might* say to those asking "is it safe?": If you are using the commonly used 800MHz+undervolt setup, and your usage pattern is that of an average user then your chances that your device will survive at least 12 months after enabling that OC are for sure better than 50%.

@freemangordon: I mostly agree with you, even partially with your chain of evidence about edge steepness. You're missing just one detail about SmartReflex: it's not only the automatic control of regulators in twl4030, SM is also a whole bunch of measures *on OMAP* chip, one of which is (AIUI) that there are individual micro "regulators" for voltage/current/working-point of each gate or even transistor. Those can't get switched on or off, they are always active. And again AIUI the twl4030 regulators and all the undervolting just determines the *input* voltage to those micro regulators. So if you really want to undervolt the logic gates, you'd need to lower the VDD input voltage to those regulators to a level where they cease to function, which can't be a sane thing in my book. All the SM that you can enable or disable in twl4030 is just meant to operate those micro regulators on a voltage drop as low as possible, to save energy (which btw only makes sense because the switching regulators in twl4030 are of better efficiency than those SM linear micro regulators).
Regarding temperature, while we're talking energy consumption, I agree that it for sure makes a lot of difference. Nevertheless the main factor is current density and the fact that it has a certain threshold above which EM goes through the roof while below it there's almost no EM at all. On OMAP3430 it seems this threshold is somewhere in the range 500..600MHz. I'm taking these values as well as my idea that they are independent from the SoC's "peripheral components" from the fact that the datasheet doesn't mention any of those as being relevant for the calculation for estimated lifespan at different clock speeds. Sure exceeding max die temperature will massively increase EM even on lower current densities, but the datasheet clearly says that up to the maximum allowed operating temperature and core voltage and whatnot the CPU still can live for 100.000h@500MHz and only for 23.000h@600MHz. I think if there'd been a way to safely extend that period (or increase clock speed while keeping the period) then TI for sure would've mentioned that, as they are interested in selling chips with the best possible specs.
I still fail to see any competence in N900 community that would allow to invalidate what TI came up with about maximum ratings of their chips, and speculating about what will happen if we deliberately go beyond those specs is just that: speculations. I'm feeling my speculations are based on sound facts and reasonable extrapolations, and they make me think a OMAP3430 will last no longer than 300h *running* at 1GHz clock speed, no matter what you do to it, as long as it works at all at that clock speed and not simply degrades to a random generator due to too low core voltage. After that timespan of CPU running at that clock speed I'd expect ~5..10 of 100 devices starting to expose random failures which make the device useless.

/j

Re: overclocking,,it is dangerous??
 

so many infomation i learned about this conversations..

Re: overclocking,,it is dangerous??
 

While both freemangordon and joerg_rw got their points, I would like to mention my totally uneducated observation, based on ~10 years practice of overclocking desktop (later also some notebooks) components. If I recall correctly, "from the beginning of (overclockable hardware) times", every manufacturer (like TI) tend to intentionally "underestimate" lifetime, especially when it comes to frequency increase. I don't know how well this apply for such miniaturized things as our SoC, but data-sheets were "scarring" us with xyz times degraded lifespan with every-10%-of-frequency-overclock, since times of early Durons.

Practice seems to prove that it's a lie. Explanation is simple - it's more fun to sell same chip factory-overclocked, as new one (or, sell something *very* of very similar architecture, with almost-cosmetic changes in design).

joerg_rw assumption of TI willing to sell thing with best specifications possible would be real in "perfect world", but in our reality it may be just false - IMO, TI (and other manufacturers) got quite $$$ interest in lowering declared lifespan of it's products. *Especially* when overclocked beyond point, that is becoming base frequency of their (planned) brand-new, 5x times more expensive (at least on introduction moment) "new" higher clocked product, which is - in reality - almost identical to old one.

The same things happen in medical industry, mind You. Many "revolutionary" next-gens of medicals for serious illness are augmented old ones, with little effect of extending lifespan of patients (other than placebo effect...).

Sorry for quite harsh patient-CPU metaphor, and keep in mind that this post was sober speculation , totally uncertified by other means that personal experience.

Ps.

I still got working machine with 600 mhz Duron running @ 1000 mhz (working as router/media server/whatsnot combo, 24/7, from so many years that I can't count it...), and Athlon XP 1700+, 1400 mhz, running @ 2400 mhz, both still able to pass all CPU stability test without single glitches. Yea, I know about working/sleep time (ho ever, AIUI, such mechanics were much less reliable in times of Durons), but it seems to me that according to manufacturer specs, my oldie CPU/s are "this" fire station 100-years old carbonate light-bulbs equivalent.

What makes me doubt such a luck, though, is that it happens with every device I overclock - always doing hundred of hours (in total) tests, monitoring and tweaking, never leaving it with even shortest instability. So, it seems to me, that over-clocking is not much different from other "life" activities - if You're doing it with brain and some knowledge, You'll be fine. Which I can't tell about some people here, stating in their signatures about running their devices @ 1000 or 1150 locked ;) (no offense to anyone, it's free world)

/Estel

Re: overclocking,,it is dangerous??
 

@Estel

As I've mentioned, TI was selling a 3440 with an A8 clocked at 800MHz along with the 3430. It's hard to believe they would sell a chip with a dramatically lower lifetime or that it's a completely new design which would raise r&d and production costs. Also, going by what they said, 45nm A8 is best at 800MHz and they sell a 1.2GHz version. Do you think it has a 10h lifespan at such a frequency? Scorpion core must have 2h lifespan at such high frequencies since it's a similar design, just pushed higher out of factory for competitive reasons. They have to somehow stop overclocking and force you to buy a new device with their "faster and new" chip.

EDIT: OMAP 2420: N95/8GB, N82, E90 = 332MHz
N800/810 = 400MHz

Re: overclocking,,it is dangerous??
 

I can absolutely prove that driving a car is not safe. The statistics are completely obvious. Anybody who thinks that driving a car is safe is insane. The easiest way to save huge numbers of lives every single day would be to close down the highway system. Who can disagree with me? Yet, I drive a car.

And I overclock. Why? Because the benefits outweigh the risks. Those who want to magnify the supposed damage of overclocking carefully steer away from mentioning the overwhelming positive experience on this site of people who overclock. I think it is debatable whether even the few incidents of supposed damage from overclocking are accurate — look at the messages and you will see that the people claiming the most damage are running everything but the kitchen sink and it's very difficult for me to tell that overclocking must be the smoking gun.

If anyone can give me instructions on how to damage my N900 with overclocking, I will strongly consider trying it out. But, in scientific discussions when you try an experiment the results of that experiment should change the beliefs of the people proposing the experiment – otherwise, the experiment is meaningless. Unfortunately, I think we are seeing a faith-based argument against overclocking. It is impervious to reason. Any one who cites their own experience is talked about with contempt, like experience has nothing to do with it.

Re: overclocking,,it is dangerous??
 

I'm not an expert on the subject, but I've done some testing that could be related to CPU wear a year ago or so.

I ran nbench a multitude of times with several clock/voltage combinations. While running the tests, I monitored current_now as reported by the bq27x00_battery module. Unfortunately I've lost the spreadsheet with the exact results, but I do still remember my observations:

A higher clockspeed with substantially lower voltages required a lot more current from the battery than a lower clockspeed with substantially higher voltages.
Setting a lower or higher voltage for the same frequency didn't nearly affect the used current as much as setting a lower or higher frequency.
This is with SmartReflex turned off in software.

These results seems to support joerg_rw's post that the SoC does have micro regulators that affect the current. This in turn seems to suggests that the user set voltage isn't nearly as much in play as in traditional desktop/laptop overclocking (and thus overclocking the N900 can't be compared to that).

I would be grateful if someone* could reproduce (or disprove) the results of my test. Nbench for the N900 can be found here. Personally, I think the higher current_now is enough 'practical' prove that OC'ing does wear out the CPU much faster than running the cpu at stock speeds, pretty much regardless of whether you're undervolting or not.

* do we have a volunteer?
--

By the way, I don't know how accurate current_now from bq27x00_battery is, but the fact that it went up significantly with higher frequencies at least means something I guess. Testing was done with SSH over USB (offline mode, display off).

Re: overclocking,,it is dangerous??
 

Exactly. I am quite confident that no matter how much we overclock the N900 within the boundaries of what the Power Kernel allows, the CPU will outlast pretty much anyone's life time usage of the device. Yes, you can try to be scientific and calculative about the whole theory behind overclocking and how it can damage or shorten its lifetime. But my point about overclocking being safe is far more correct "till-now" than the ones who are over-cautious and saying overclocking is dangerous. If suddenly people's N900 start burning/dying tomorrow, I'll stand corrected. But I doubt it will be the CPU that burns out first.

N900 has been out for about 23 months now and overclocking started around 18 months ago I think. So we only have 18 months of data to go by. I am fair confident in saying we so far had less than 0.1% (if that) of those who overclocked that had their N900 physically damaged by it. I'm throwing imaginary numbers out of my head so please correct me if you have more accurate numbers. :p

I've been overclocking CPUs since the 486 days. (My motherboad didn't have any option to overclock my 286 and 386...) I've yet to have a cpu die on me and I gone through over 20 CPUs myself and many many more for all my family, relatives and friends that I've built the PC for. (I overclocked every single one of them before letting them use it. lol)

Mobile phone overclocking is fairly new concept and we don't have the flexibility to better "cool" it or run it at different FSB etc. I've only overclocked a handful of Android phones (including the SGS2 where I got mine to 1.5GHz rock stable) and the N900 so far. So not a whole heap of personal experience yet but I might still be up there and be above-average.

I understand some people going totally against it. But I don't understand when you just go against it without any real strong evidence or statistics to back it up. I also don't have a proper statistic for you guys but the history so far is definitely in the favour of the overclockers I think..... We will know more in a few more years.... as that's the argument... I guess only time will tell...

(This is a debate where no one can win. It's like religion it seems. lol)

Re: overclocking,,it is dangerous??
 

@jakiman

They go against overclocking and saying how their lifetime is going down the sewer, but wasn't the SGS II overclocked like half a month prior to launch? There was no time to implement a new SoC in half a month. Going by what joerg_rw says, we should sue Samsung for lowering our CPU's lifetime. Did anyone complain? No, the phone got praised for being the fastest in the mobile industry.

Based on this, the question rises, how much are this phones actually downclocked in the cheapest SoC variant? Desire Z can go from 800MHz to 1.8GHz even 2GHz, a crazy jump. Apple, iirc, officially stated that 3GS A8 was downclocked to 600MHz from the actual 833MHz (3440 also 800MHz). How many Moto Droids have actually died at 1.3GHz. People have been benchmarking the said frequency for hours and playing emulators (same with the N900)?

BTW, weren't you the one that ran min max 1GHz on your N900 for a while?

Re: overclocking,,it is dangerous??
 

@iDont - it is obvious that runnning CPU constantly on higher frequency will increase average current (which is what bq27x00_battery measures). But average current is not the same as peak current, which is the one responsible for EM. And running syntetical benchmarks has nothing to do with real life usage patterns.

I really hope you can find your tables (or someone to do measurements again) to see how voltage affects current, because quantities as "lower" and "higher" may work in fuzzy logic, but won't work here.

Re Smartreflex - I am in process of educating myself about that technology and kernel support for it. So far it seems that it CAN be turned off, just not sure if setting sr_vdd1 and sr_vdd2 to zero is enough.

Re: overclocking,,it is dangerous??
 

That's right. Even the iPhone4 was downclocked to 800Mhz from the 1GHz A4 which iPad2 uses. It's a matter of striking good balance between heat, battery life and performance. These mobile phone SoC's are made with much higher yield than what they actually are made to run at to ensure they are stable even while they are under a blazing summer heat with no air circulation. So it's even better than the desktop PC CPU's IMO.

Yes, I was the one running my N900 at 1.1GHz for both min/max. Heck, even Lehto (the first one ever to overclock the N900 at TMO afaik) told me he does this. But this isn't something I would recommend for everyone unless you know the risks. (possibility of instability, hand burning, exploding...just kidding...hehe..) But yeah, it should only be done if you are experimental and fearless. :cool:

BTW, I got my N900 replaced this week as my USB socket ripped out. (my kid stomped on the cable/n900 while it was still plugged in) This new one I have is even more stable than my previous one as my last one was quite unstable at 1.15GHz using ideal voltage. But this new one seems to be rock stable. My last one never skipped a beat at 1.1Ghz using xlv voltage. So this one should last me even longer maybe as long as my kid doesn't kick my N900. :D

I'm actually eagerly waiting for someone to overclock the N9.
I reckon 1.2GHz is just guaranteed and 1.4GHz is highly possible.
So yeah, bring it on. I'll risk my N9 for the community. :D

(AFAIK, I was the first person Lehto gave his custom kernel to to overclock the N900 other than his own)

Re: overclocking,,it is dangerous??
 

@jakiman - just have in mind that 3630 SoC uses 45nm, not 65nm as 3430, i.e. it is more fragile and susceptible to EM ;)

Re: overclocking,,it is dangerous??
 

hehe. Yes. But it also means it's is more efficient. Smaller fabrication so far has pretty much always shown that it allows faster frequency for the same amount of power. (or even less power) If the 3630 SoC is anything like Samsung's SoC used in SGS1 (similar Cortex A8), it should be able to handle at worst 1.2Ghz. But I'm an optimistic so I want my N9 running at at least 1.3GHz. Should make rendering web pages, loading apps, multi-tasking a bit smoother and faster. :D

Re: overclocking,,it is dangerous??
 

Heat and power consumption are stopping them from upping the frequency at a larger fabrication process (remember, it's a phone). Anyhow, you'll surely get 1.3GHz out of the 3630 since the Droid 2/Milestone 2 are capable. Also, 3630 can come out of the factory as 1.2GHz; clock range is 600-1200MHz.

http://en.wikipedia.org/wiki/Texas_I...ts_OMAP#OMAP_3

I sure as hell wanna know what the actual clock of the A9 is inside the Vita.

Re: overclocking,,it is dangerous??
 

Very interesting thread!

To understand why anecdotal evidence is really useless here, one has to remember that both the quality of a single chip (expected time to failure) and the time to failure itself are random. This is why TI uses margins in the clock speed, and this is why some chips will stand for a very long time OCed, while other will fail quickly. (randomness of quality is obvious when you look at maximum stable clock: we have a lot of feedback on them, and they vary from 700 to 1200 MHz for different devices)

exemple 1 (N900 related, invented numbers):
let's say that the average chip reaches an expected time to fail of 4 years at 800MHz, but the variance is such that 1% of the devices achieve these 4 years at only 600MHz, while another 1% will do it at 1000MHz.
Most of the feedback on OC at 800MHz would be largely positive (especially after 1 or 2 years), and yet such OCing would be unthinkable for the manufacturer, and the lifespan of a significant number of devices would be reduced.
I have fabricated the numbers, but you can't discard this possibility with today's knowledge.

example 2 (not N900 related, real numbers):
To show that quality of processors in a manufacturing process vary VASTLY between individual chips, within the same batch, factory, etc.. Let's take a look at the recent apparition in the market of "unlockable cores": 2, 3 and 4 core chips are now identical, produced by the same chain, and all ship with 4 physical core. BUT, there are so many cores that fail the post production quality tests that you they can base almost all of their 2 and 3 core production on the failures/remains of the 4 cores chips.
Failling the quality test does not mean that the chip won't work. It doesn't even mean that it won't work as long as one that has passed. It means that its failure probability is too high (probably like 1 or 2% for the warranty period)
Now, think of this in the context of "same chip, different clock speed, different price".

well, my point is, whatever people told you or experience:

• OC is safe for some devices
• OC is not safe for some devices
• You can't tell in which category yours is.

PS: lights bulbs mostly wear when switching them on, because of the mechanical constraint due to the violent, uneven temperature changes. The wear by evaporation of the heated metal is much less significant. So if you never switch a light bulb on and off, it is much more likely to last 100 years ;)