Okay, something a little different. This was written on Eileen-II, but outside of the apartment, and definitely not plugged in, i.e. just running on batteries.
I just wanted to see how long Eileen-II could last without being plugged in, doing some programming, the kind of things that I would normally like to do when I'm roaming outdoors and wanting to do something more different from just reading.
I must say, the battery life is... interesting. I unplugged Eileen-II at around 0900hrs, packed her away, went for the Good Friday service at church till about half-past noon, then set up shop at Morganfeld's @ Buona Vista at about 1254hrs. At that point, the power had fallen to around 91%. Eating/reading for about 30 min, then I spent the rest of the time working on Eileen-II, with only the tethered Wifi turned on only at about 1602hrs.
As at 1640hrs, the battery is now at 62%. So it works out to around 7% or so of battery capacity per hour of ``active'' work.
That's actually not too bad. In fact, considering the heavy machinery that is within Eileen-II, I am rather surprised at just how well the battery life is. Eileen-II also fits in my back-pack---I was a little worried because she is 15", as compared to Edythe-III who is around 13.3".
Now, for some more gory details.
I set the Windows power plan to using ``Balanced'' instead of the hidden ``High Performance'' setting. In addition, I used ThrottleStop again to adjust the offset. The old value that I was using was −90.8 mV, which was too aggressive---I kept Eileen-II up overnight while setting a tool to monitor the CPU voltages. The lowest untouched CPU voltage that I saw was around 0.56? V. I knew that any CPU voltage lower than 0.500 V was an issue for display instability, and with the recorded value, I decided to undervolt just enough to give myself about 0.02+ V of leeway.
So I undervolted to ``only'' −40.0 mV instead. I left all the TurboBoost ratios back to factory defaults for all four profiles, reasoning that I don't care about spikey high temperatures (with the workaround of using an external keyboard to play games that ended up using all cores all the time), but deliberately set them to the tweaked versions for the profile that was designated ``Battery'' in ThrottleStop. I also set the SpeedStep EPP to be more aggressive in down-ratio---a setting of 255 instead of the default 128.
So far, everything seems good. I'm not going to complain.
In many ways, I think that CPU design has really evolved quite a fair bit compared to the old days of the 80486/Pentium. The last time I studied CPU features in such detail was back in my undergraduate years, when I was still actively studying CPU design to better understand them for programming. But in those days, I was looking at CPUs from the perspective of performance rather than the balance between performance and being power efficient. CPUs have gone a really long way in that department---I was still under the mentality that a single battery charge can last a laptop at most 4 hours brand new, with an average use-time of about 3 hours before degrading down to just 2+ hours.
And just as I hit the publish button, the power capacity is 59%.
That's all I have for now. Till the next update.
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