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3. What Else?

3.1. How to test whether it works

Ok ... you use one of the described powersaving possibilitys and you want to verify, whether it works. Here are two ways to check it:

If you have temperature controlled Fan on your CPU-Heatsink, you could check for the noise level of the Fan to see whether it works or not. After a few idle minutes you give the CPU somthing to do.

I normaly do it like this:

  1. get superuser (root)
  2. cd /usr/src/linux
  3. and give the computer something to do: while true; do make clean; make bzImage; done
After about 20 or 30 seconds you should notice that the noise of the fan is getting louder while the fan is getting faster. Don't forget to end the while-loop after some time ( a few minutes) with STRG-C.

The same procedure as above works also with a monitoring program for the cpu-temperature (like lm-sensors, xmbmon and rtsensors).

3.2. Known Bugs/Problems

There are two known bugs in the Athlon/Duron processor. This is number 11 and number 14 in the AMD Athlon Processor Revision Guide. It looks like the Athlon XP is significantly less often affected by these bugs. So if you have an Athlon XP you are on the lucky side (like me).

There could be following problems (caused by the bugs):

  • skips during sound playback

  • skips and slowdown during video playback

  • slowdown of the ultra-DMA harddisk transfers

  • system hangs

  • USB problems

  • someone reported a high cheeping noise

Sometimes a BIOS-update will help (it exists as a workaround for bug 11, which could be done by the BIOS). But as far as I know there are only a few boards out there which have this workaround in the BIOS.

For the Asus A7V133-C, it is known that the BIOS-option PCI master read caching will solve most problems when it is enabled. So look at your BIOS to see whether it has such functionality.

It is also known that on some boards, the BIOS option Delayed Transaction solves some of the problems. You may want to give this option a try too.

WARNING: On boards with KT133A, this could enable the famous VIA-Southbridge bug!

From a Newsnet post, regarding Asus A7V:

  • without delayed transaction: sound-skips and TV-skips

  • with delayed transaction: no sound skips and only slight TV problems

  • with delayed transcation and master read caching: nearly no TV problems and no sound skips at all

There are other causes for problems:

  • the PSU is not strong enough to handle the fluctuations in the power consumption of the processor/motherboard

  • some motherboard voltage-regulators could have the same problems like the PSU ;)

  • you have a K7S5A (as far as I know, this board could be really wierd when power-saving is enabled)

If you have minor problems with power-saving enabled, and nevertheless want to use power-saving, you can enable the power-saving by default, and turn it off if you want to playback music, watch TV, ...

3.3. Fix for sound skips and other problems

Thank you to Michael Hamilton for submitting me the idea how it works.

The working of this Fix was confirmed by two People, so it looks like it works, but it may not work for everyone. Please feel free to submit further experiences!

Lets go: It looks like at least the sound skips are curable by maximizing the pci latency timer of the device.

First you have to find the "pci-address" of your Soundcard. This could be done with lspci. You have to look for something like "Multimedia audio controller" or "AudioPCI". Take the "pci-address" of the device (looks like something like that: 01:06.0 -> it stands for: bus:slot.function) and maximize the latency timer for it. This is done by setpci:

setpci -v -s "pci-address" latency_timer=ff

For additional Information on the Latency Timer you could look here.

Maybe this works also for other problems like USB-Problems and Harddisk-Transfer-Slowdowns, but this hasn't been tested for now. Feel free to test it (but don't blame me, if it doesn't work or makes everything worse) and report whether it works. The problem is, that i have none of this problems and so can't test this by myself.

If it works, you have to perform this setpci command at every startup/reboot of the Computer. So it would be wise to put it in one of the init-scripts (after the driver module is loaded!).

3.4. Another Fix for sound skips and other problems (on some Via-Chipsets)

Thank you to Wijatmoko Prayitno for submitting this!

The working of this Fix was confirmed for KT266, KT/KM333 and KT/KM400 Chipsets. It may also work for other Via-Chipsets. Please report if it works on other Via-Chipsets !

This is quite easy and works like the Commandline-Hack for enabling the Powersaving:

Soundfix on KT/KM333 and KT/KM400 Chipsets:

enable: setpci -v -H1 -s 0:0.0 70=$(printf %x $((0x$(setpci -H1 -s 0:0.0 70) | 0x08)))

disable: setpci -v -H1 -s 0:0.0 70=$(printf %x $((0x$(setpci -H1 -s 0:0.0 70) & 0xf7)))

If it works, you have to perform this setpci command at every startup/reboot of the Computer. So it would be wise to put it in one of the init-scripts (after the driver module is loaded!).

3.5. ToDo

Adding more chipsets and more informations to this document.

Adding some Informations on the Powersaving System of the Athlon64 and Opteron CPUs.

Adding some Informations on Notebooks and Power-Saving.

3.6. Translations

Translations into different languages also exist. At the moment, some of them are not up to date.

Hungarianby Zsolt Mocza

Spanish by Carlos Mayo (very out-dated)

brasilian Portuguese/Portuguese by Bruno Buys

French by Mathieu Pillard (very out-dated)

Italian by Maurizio Fantino (very out-dated)

German (only parts) by Fabian Mohren

Japanese by Seiji Kaneko