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. |