[ltp] X61 power consumption

[Richard Neill]

James Knott wrote:
> Leszek Koltunski wrote:
>>
>>> I think mostly because the Windows driver writers have all the hardware
>>> specs. It is not only an issue on ThinkPads.
>> Ok, I understand that, but couldn't we ( Intel, Lenovo ? ) have an
>> electrical engineer actually *measure* how much power does each chip
>> eat under Linux, and then under Windows, so we could point the finger
>> at the culprit rather than saying 'well, I think it's PCIe... or maybe
>> graphics' ?
> That would be rather difficult, as in order to measure the power, you
> have to measure current and that means cutting the power connection to
> the chip, to insert the meter in series.  Now if you wish to volunteer
> your ThinkPad to be butchered...  

Not *quite*. If you can find a resistance of even a few miliOhms, (eg a 
short PCB trace), you can measure the current by measuring the 
resistance and then the voltage across it. (If you can measure one 
microvolt over a 1 milliOhm resistance, you can get measure 1mA; this is 
easy with an op-amp)

Or, you could point a thermal camera (or IR thermometer) at it and 
measure heat dissipation.

You could also (possibly) get a handle on current by measuring the 
B-field with a Hall-effect sensor.

In general though, if you say "Ouch" when you touch it, that's the 
component that's taking the power ;-)

Richard