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powersaving_a7v333 [2013/01/15 15:23]
krakonos 		powersaving_a7v333 [2014/11/23 16:29] (current)
krakonos
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 +~~REDIRECT>http://krakonos.org/p/powersaving-with-a7v333~~
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 ====== Power savings on A7V333 ====== ====== Power savings on A7V333 ======
 I have some old 320GB hard drives for some time now. They are all IDE and all unused. I decided to make some backup machine which would sit at home and be handling daily backups. Here is what I have: I have some old 320GB hard drives for some time now. They are all IDE and all unused. I decided to make some backup machine which would sit at home and be handling daily backups. Here is what I have:
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 ==== Undervolting ==== ==== Undervolting ====
 It is only natural that so underclocked system would not need the default 1.75V. After googling a little bit, it seems that these CPUs can run @1.6GHz with 1.5V! Unforunately, the BIOS is made for overclockers and only allows overvolting the cpu (all the way up to the 2.3V!), but not undervolting. On board, there are however jumpers that allow you to set lower voltage. Unfortunately, it goes only to 1.7V, which gained me nothing (it is not that surprising, since the athcool essentialy allows cpu powerdown when idle). It turns out that you can undervolt the CPU down to 1.2V via the jumpers, it's just not documented anywhere in the official manuals. See below for table of undocumented jumper settings (keep in mind, that althoug bios offers you software choice when jumpers are set to lower voltages, the choice is always ignored and the hardware takes precendence). Undervolting to 1.5V gained something around 3W, down to a total of 68W. Further undervolting to 1.3V did not decrease power consumption, and at 1.2V the machine was unstable (freezed in bios, could not detect drives on Promise controller). I left it at 1.3V. It is only natural that so underclocked system would not need the default 1.75V. After googling a little bit, it seems that these CPUs can run @1.6GHz with 1.5V! Unforunately, the BIOS is made for overclockers and only allows overvolting the cpu (all the way up to the 2.3V!), but not undervolting. On board, there are however jumpers that allow you to set lower voltage. Unfortunately, it goes only to 1.7V, which gained me nothing (it is not that surprising, since the athcool essentialy allows cpu powerdown when idle). It turns out that you can undervolt the CPU down to 1.2V via the jumpers, it's just not documented anywhere in the official manuals. See below for table of undocumented jumper settings (keep in mind, that althoug bios offers you software choice when jumpers are set to lower voltages, the choice is always ignored and the hardware takes precendence). Undervolting to 1.5V gained something around 3W, down to a total of 68W. Further undervolting to 1.3V did not decrease power consumption, and at 1.2V the machine was unstable (freezed in bios, could not detect drives on Promise controller). I left it at 1.3V.
 +
 +It seemed to work fine, but sometime during emerging stuff (relatively few things, lzo & openvpn for example), the gcc would segfault on different places. I decided it is time to volt it up back to 1.5V. Segfaults vanished.
  
 ^ Voltage ^ Jumpers ^ ^ Voltage ^ Jumpers ^
powersaving_a7v333.1358263427.txt.gz · Last modified: 2013/01/15 15:23 by krakonos

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