Overclocking / Underclocking...
Overclocking / Underclocking...
Mar 6 2004, 11:02 AM
Joined: 8-November 03
From: Birmingham, United Kingdom
Member No.: 875
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 ) 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.
Jun 10 2004, 05:33 AM
Joined: 30-October 03
Member No.: 813
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.)
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