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Foxdie
Okay I am creating this thread to alleviate the heated discussions of overclocking the Cxx0 series of Zaurus from other area's of the Zaurus User Group.

This is how I have come to understand things as an overclocker of various computer equipment. For the last 3 years I have owned a AMD Athlon 1GHz PC which has been overclocked to 1.3GHz with no problems. The CPU stays under 45'C / 115'F (a CPU is considered to be overheating at 65'C / 150'F or above) no matter how hard it gets pushed, on these grounds I consider myself quite knowledgible about overclocking devices.

When you overclock something you have to take 3 factors into consideration. Stock (original) CPU speed, what cooling the CPU has and how much the CPU is going to be used at any given time.

The Zaurus doesn't have much in the way of cooling, however because the XSCALE CPU is designed for low voltage and it doesn't have a FPU it also means that it's not going to generate as much heat. Overclocking can void your warranty (but only if you tell the retailer you overclocked it wink.gif) and can damage your CPU IF you push it too far.

Within the latest Cacko ROM you have 5 fixed overclocking options which are safe to use on any Cxx0 Zaurus, provided you follow the guidelines later in this post. First of all I would like to take you all through what CPU clock speeds the overclocking utility permits you to set.



As you can see, when you overclock or underclock the Zaurus you are also changing the values of the RAM (not the storage media) and the bus speeds (the speed at which the CPU communicates with other devices). No matter what value you choose there should be no corruption of data (although if this has happened please correct me, I haven't heard a report of it yet!).

People who should consider overclocking:
[list]People who run emulators eg. gnuboy

[*]People who want to use their Zaurus for Video

[*]People who need to calculate data faster, for example WEP cracking

[*]People who think the Zaurus is running too slow[list]
People who don't need to overclock:
[list]People who use PIM's eg. Calendar App

[*]People who use their Zaurus for MP3's

[*]People who surf the net and/or use WiFi

[*]People who use communications Apps like QPE-GAIM[list]
People who should consider underclocking:
[list]People who use e-book readers

[*]People who are checking email automatically

[*]People who generally want to display the same screen / image without it changing

[*]People who want to get more battery life out of their Zaurus[list]
Overclocking with the tray applet in the latest Cacko Qtopia ROM is safe. It doesn't push the CPU speed too far and there is a minimal heat increase. If you're still a little wary of overclocking but feel it may help you here is a guide based on model:

C700: You can run it at the Overclock level but only for short periods of time (no more than 15 minutes), it pushes the memory clock quite high in relation to it's stock speed. The default for the C700 is "Default (PXA250)".

C750, C760 and C860: You can run it at the Overclocked level for as long as you desire but don't use it for more than an hour if you wish to keep your Zaurus in top condition. The default for this series is "Default (PXA255)".

Remember, when you're charging your Zaurus battery, extra heat is generated, due to this you should cut the above overclock time in half if you have your Zaurus connected to it's charger.

Cool down time for all Zaurus is 30 minutes. After 30 minutes has gone you can safely overclock again. Be warned though that repeated overclocking / underclocking can cause heat expansion which can physically damage your Zaurus.

Other ROM's have the ability to set the clock speeds differently, you can set the CPU as high as you want with it. As such this is very dangerous. You should NEVER overclock your Zaurus more than to 471 MHz (the next step up is 530 MHz which is too far). Use the table above as a guideline for the maximum safe overclocking speeds!

Please feel free to ask any questions, and also before you post PLEASE use your common sense when typing your posts. Any post that is deemed by myself or the other ZUG team as inappropriate or in any way offensive it will be deleted.
Anonymous
Ok...I'll bite. Excellent post. Very well thought out and presented. But again...issue with the word "safe". You said "Overclocking with the tray applet in the latest Cacko Qtopia ROM is safe." But then you go into some guidelines on how to make over-clocking not do too much damage over the long haul. I would recommend you change the "Overclocking with the tray applet in the latest Cacko Qtopia ROM is safe" to "Although Overclocking can be risky and void your warrantee, here are some guidelines that will help lengthen the life of your Z when over clocking and minimize its effects, if any."

Its just a recommendation.
realistic_dragon
Presumably installing this ROM on any device will leave it in a normal clock state by default unless you change it?
offroadgeek
If you ask me, this is just a matter of symantics. Take bungie jumping for example... if someone tells you that bungie jumping is safe, and you should try it, would you not first do some research to better understand what you are getting into prior to taking your first jump?

the same should apply with overclocking... if you are thinking about overclocking your Z, do some research of your own (more a suggestion to others, because if you are the same "guest" that is in the other thread, you have clearly shown that you've done your own research on the topic), then make an educated decision as to whether you will use this feature or not.

That said, I agree with you in warning people about using the word "safe" with overclocking. Especially if you are a company selling a product and could possibly face legal issues by possibly misstating the capabilities of the product. However, foxdie and maslovsky are simply individuals with educated opinions, and neither of them are providing any guarantees that overclocking won't damage your processor or any other components.

Lastly, there are some fundamental consumer responsibilities when purchasing a product, such as understanding the warranty. If a consumer doesn't fully understand their warranty, and what could void the warranty before doing something like overclocking, then it's their ignorance that is to blame, not a post on a zaurus forum.
Foxdie
QUOTE
Presumably installing this ROM on any device will leave it in a normal clock state by default unless you change it?


To my knowledge no ROM is supplied with overclocking enabled by default, if it is the ROM developer is a fool. Not many people want or need to overclock their Zaurus.

The Cacko Qtopia ROM is no exception, the ROM is definately supplied with the CPU set to run at default speed. Even when you reboot the CPU is set to run at default speed as a precaution.

You can check what speed your CPU is genuinely running at by going to the CPU (third) tab on System Info on the latest Cacko Qtopia ROM, or you can click on the little traffic light icon by the clock to select a CPU speed option.
Randy_003
umm. just curious Foxdie, how slow does Gnuboy run on your C760?
Foxdie
Admittedly there's a problem. I can't seem to start any games due to key bindings, there's no middle button on the C series (to start games, the joypad style control on the 5x00 series).

Running at default speed it runs slightly slowly, the sound has micro-skips. If I run it at the overclock level it seems to run at 100% emulation speed.
raybert
Foxdie, have you tried the space bar? The middle button on the 5x00's mapped to the space key. I've found that most apps that used the middle button on the 5x00's respond to the space bar on the c-series. It's a little akward to use though for some apps.

~ray
ScottYelich
I'd remove the words "safe" .. just for legal / liability reasons. :-> I mean, people *are* crazy
(What? you mean this gun could actually HURT me? I thought you said it was safe!!!!)

Also, are you sure about the overclocking the 700 pushing it too much? I thought it was
also 397mhz... default... just had cache disabled? pxa250 = 397, cache disabled
pxa255 = 397, cache enabled?

seems 471 is the same jump for both, if that above 397MHz is true ( for both)

Scott
CoreyC
Nice debate going on here smile.gif

I have not yet felt the need to overclock my c760, but I did play around with it a little with my sl5600 when using emulators and some multi-tasking like listening to shoutcast streams and browsing with opera at the same time. My c760 can do this w/o any problems while the sl5600 had some trouble... (Overclocking didn't help BTW)

On my sl5600 you can feel the heat difference while overclocking, and I noticed only a minimal change in preformance. I wouldn't recommend overclocking the 5600 at all.
Stubear
QUOTE
Overclocking can void your warranty (but only if you tell the retailer you overclocked it wink.gif) and can damage your CPU IF you push it too far.


You don't need to tell them. Overclocking for any reasonalbe length of time causes changes to the cpu that are noticable. Not sure what the changes are, but I used to do proof-reading for a tech at Toshiba in Japan and was asked once to proof-read a letter telling someone that they wouldn't honor the warranty on their laptop cause it had been overclocked - Toshiba stated that this had caused the problems and they weren't gonna fix it.

Stu
maslovsky
QUOTE
Overclocking for any reasonalbe length of time causes changes to the cpu that are noticable


Sorry, but this is nonsence.
Foxdie
QUOTE
QUOTE
Overclocking for any reasonalbe length of time causes changes to the cpu that are noticable


Sorry, but this is nonsence.


Actually what Stubear said is true, but only if you overclock too far. Overclocking an Xscale CPU greater than 471 MHz will cause it to overheat and PERHAPS warp the CPU packaging. The next stage of overclock from 471 MHz is 530 MHz which will void any warranty.

There is also the argument that you can't tell an overclocked CPU from a badly cooled normal CPU. I think that the heat expansion will cause micro-fractures in the CPU casing that can be examined under a microscope. Manufacturers should have taken this into consideration.

These are all extreme suggestions though wink.gif
Stubear
QUOTE
QUOTE
Overclocking for any reasonalbe length of time causes changes to the cpu that are noticable


Sorry, but this is nonsence.


Can you prove this? I'm just stating what I was asked to proof-read. I've seen several laptops where oveclocked cpus melted holes in the case. Are you telling me that you are 100% positive that the increases heat caused by overclocking leaves absolutely no traces?

Stu
lardman
There must come a point where the extra heat does do damage, it's just trying to work out what that point is. I image there are some overclocked speeds which will never do any damage (the heat dissipation into the atmosphere/rest of the Z is sufficient to stop it), and some which will eventually (or even very quickly).


Si

P.S. I spell-checked "dissipation" in MS Word to check I'd spelled it correctly and the thesaurus gave me the following as alternatives: debauchery, indulgence, rakishness. Is this some strange Americanisation or did I get the wrong word ;-)?
maslovsky
QUOTE
Can you prove this? I'm just stating what I was asked to proof-read. I've seen several laptops where oveclocked cpus melted holes in the case


I don't beleieve that. Even if that happened, this only means that those laptops were poorly designed and did not provide good CPU cooling. Most likely the manufacture used desktop CPUs, which produce much more heat instead of their mobile variants, specialy designed for laptops, with low power consumption and heating.

QUOTE
Are you telling me that you are 100% positive that the increases heat caused by overclocking leaves absolutely no traces?


I've been overclocking my CPUs/memory/Video Cards/etc. for years. I have not trashed a single pice of hardware. Yes, you have to think and understand what you're doing.

QUOTE
There is also the argument that you can't tell an overclocked CPU from a badly cooled normal CPU. I think that the heat expansion will cause micro-fractures in the CPU casing that can be examined under a microscope


Come on, do you realy imagine a warranty manager poking around your laptop with a microscope smile.gif

QUOTE
P.S. I spell-checked "dissipation" in MS Word to check I'd spelled it correctly and the thesaurus gave me the following as alternatives: debauchery, indulgence, rakishness. Is this some strange Americanisation or did I get the wrong word


Better ask Billiy smile.gif
Stubear
QUOTE
QUOTE
Are you telling me that you are 100% positive that the increases heat caused by overclocking leaves absolutely no traces?


I've been overclocking my CPUs/memory/Video Cards/etc. for years. I have not trashed a single pice of hardware. Yes, you have to think and understand what you're doing.


You didn't answer the question - did you even bother to read it correctly? I didn't ask if you had trashed anything, in fact I never mentioned damage, I asked if you were 100% positive that overclocking leaves no traces.

I never said overclocking was bad, I've got several desktop units overclocked - one of them has been overclocked for 3 years, but I can change the cooling in a desktop - you can't do that in a laptop or pda.
Never trashed a unit due to overclocking, but have trashed a video card trying to remove the heatsink to put a better one on so I could overclock it.

Stu
Stubear
QUOTE
I spell-checked "dissipation" in MS Word to check I'd spelled it correctly and the thesaurus gave me the following as alternatives: debauchery, indulgence, rakishness. Is this some strange Americanisation or did I get the wrong word ;-)?


Right word, the thesaurus gave you the alternatives for a different definition.

dis·si·pa·tion n.

1. The act of dissipating or the condition of having been dissipated.
2. Wasteful expenditure or consumption.
3. Dissolute indulgence in sensual pleasure; intemperance.
4. An amusement; a diversion.

Stu
lardman
I ought to invest in a dictionary and thesaurus for the office, Winword has its limitations :-)
Anonymous
Debauchery, indulgence and rakishness are all American qualities. But there's no relationship to dissipation (and you did spell it right). smile.gif

John
maslovsky
QUOTE
I asked if you were 100% positive that overclocking leaves no traces.


Yes, if you know how to do it right.
Anonymous
QUOTE
[Yes, if you know how to do it right.


Time for some expertise here. I keep reading all of these theories from so called "experts" only because they have overclocked before.

I personally work for Broadcom in the engineering department. We design chips and thier specifications. Many of the chips we design are for embedded use, such as routers, PDAs and cellular phones. One of my jobs is to help define a chip's specifications and limits. Maslovsky, unless you are also a hardware engineer for chip limitations and specifications, your statement is completely unfounded. You are not aware of how different over-clocking speeds alter a chip's life or its true after-effect. Lardman and Stubear both have very valid points. Without the ability to alter the cooling within the PDA, overclocking has great risk to the unit and it is factually incorrect that it is safe. This also goes for Foxdie and others who claim it is safe. If you are capable of adding heat dissipation or ventilation, then perhaps you would have some points. But this is not possible on the Z. If others in this group are hardware engineers and work with chips and thier limitations, I am happy to engage in open discussion on the true effects on overclocking and would also be happy to debunk theories of its safety in an environment without ventilation or (dare I say) ability to "dissipate" heat.

Cheers,

EB
Prefect47
[quote]People who should consider underclocking:
[list]People who use e-book readers

[*]People who are checking email automatically

[*]People who generally want to display the same screen / image without it changing

[*]People who want to get more battery life out of their Zaurus[list]

Has anyone measured this? For instance, if all you do from full recharge to battery warning is read an ebook, how much of an improvement can you realistically (sp?) expect?
Ethereal
QUOTE
People who should consider underclocking:
[list]


Foxdie, those who are checking email automatically, how are they doing it? I posted a thread on this some time ago, but don't have the programming abilities to impement the theoretical solutions proposed in response. Is there a standard (packaged) way to set up automatic e-mail checking?
Foxdie
I assumed if the email client was set to quick load and automatically to check for emails every 5 minutes or so it'd light up the mail LED when an email was received.

I haven't tried this though so I may be wrong smile.gif
Ethereal
QUOTE
I assumed if the email client was set to quick load and automatically to check for emails every 5 minutes or so


At least on my SL5600 with Sharp ROM 1.32, the client doesn't offer the option to check automatically--there's just an option to get mail now.
padishah_emperor
For me, overclocking raises one question, "how precious is your Z?"

For me, the risk no matter how slight, is too high, not everyone has vast disposable incomes to buy new hardware every month, it took a year of hard work to save for my Z. I simply will not risk it, no matter how slight or insignificant the risk may be.

But that's me. I love my Z.

;-)
omega
I have been overclocking (and underclocking) my Z since i got it a few weeks ago. I have found no issues whatsoever. One question though, my cpu is usually always at 100% (system cpu). Is this because of the apm daemon?
tumnus
There is an idling process that makes the CPU reduce power consumption during idle cycles. The CPU isn't actually being used during these cycles, but the way it is done makes makes it look like the kernel is consuming all the CPU. Really any process/CPU monitor should ignore CPU usage from the idling process.
clofland
Foxdie, thanks for your informative post.

One question I have is, what exactly is the difference between "Default (PXA255)" and "Normal." ? I mean, I see the difference in "numbers," but practically what happens?

Is "Normal" overclocking or is it not? If so, when? When does "turbo mode" kick in?

Would this mode be considered "safer" (again, I know this is opinion) than "Overclocked" and if so, why? (Again, what is different about it makeing it safer or not any safer than the other.)

Thanks.
maslovsky
QUOTE
One question I have is, what exactly is the difference between "Default (PXA255)" and "Normal." ? I mean, I see the difference in "numbers," but practically what happens?


"Normal" is what goes between default speed for PXA250 processor (in C700) and PXA255 (in other models). I could not come up with a better name for this option smile.gif

QUOTE
Is "Normal" overclocking or is it not? If so, when? When does "turbo mode" kick in?


Normal can be considered slight overclocking for C700 and downclocking for other Zs

QUOTE
Would this mode be considered "safer" (again, I know this is opinion) than "Overclocked" and if so, why? (Again, what is different about it makeing it safer or not any safer than the other.)


Here is my opinion - you won't damage your zaurus if you use any of the overclocking options. If your Zaurus can't handle it - it'll just hang. So next tme - don;t use that option. That's all. Personaly I always keep my C750 Z overclocked.
kaos42_ze
Is there an overclockign app i can use with TKCROM ?
xatax
QUOTE(maslovsky @ Jun 10 2004, 01:56 PM)
QUOTE

Is "Normal" overclocking or is it not? If so, when? When does "turbo mode" kick in?


Normal can be considered slight overclocking for C700 and downclocking for other Zs

I still don't understand the numbers here.

When does "turbo-mode" kicks in?

Normal has a lower "normal" speed but in "turbo-mode" it's overclocked. Why there's no turbo mode in default speeds?

Thanks in advance.
xatax
YOOHOO!! Nobody? Common... I can't believe no one is interested in the health of your Z!!
pelrun
I don't know how much clearer you need it explained - the C700 has a lower clock speed than the C750/C860.

If you own a C700, then Default(PXA250) is normal, and everything above that is overclocked.

If you own a C750/C860, the Default(PXA255) is normal, and only "Overclocked" is faster. All the other options are slower than normal.

"Normal" is only called that because maslovsky couldn't think of a better term - NOT because it is any sort of default. smile.gif
Bundabrg
No I think I understand what he's asking.

What is the difference between 'turbo mode' and 'normal mode' (The COLUMN names versus the ROW names).

I've actually wondered this too..

- Bundabrg
pelrun
That would explain my confusion - my o/c applet doesn't have columns, just the basic 5 settings.

Maybe turbo mode is to do with the cache bug fix? I have an 860 so I don't have this as an issue.
bam
anyone know the stock settings and overclock settings for the 3100? I ahve found BatteryPlus(to run with cacko/tetsu) The "suggested" setting I believe are way to high. 1.6volts is too much. and my VCORE reports 0x019, not even on the BatteryPlus site details(what I can make of them. I just need a slight boost when using kino2 (some fast action is a little jumpy), perhaps I should re-encode at a smaller fps?
Hrw
2.6 development kernels in OZ have cpufreq enabled which can give automatically underclocking if machine does not need full speed.
bam
QUOTE(xatax @ Dec 12 2004, 06:22 PM)
YOOHOO!! Nobody? Common... I can't believe no one is interested in the health of your Z!!
*



put my z on steriods and crystal meth, now its running at 100mph, work you slave, work! smile.gif
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