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by unrealhoang 1168 days ago
My very simple solution is to use a smart plug and config the mainboard to wake on power.
3 comments

But then you're draining your RTC battery. I used to have to replace my mother's PC's battery every 1-2 years before I understood she was leaving it unplugged for most of the day and told her to just leave it plugged in all the time.
A modern RTC should draw such low power from the battery (tens of nanoamps to maybe a microamp) that the life of a primary battery will basically match the shelf life. Indeed, many coin cells actually have a longer life with a small amount of current draw than in a fully open circuit (in a wrapper on a shelf).
How modern are we talking about? This was a Haswell system, I believe.

All I know is that in 20+ years of maintaining computers, hers was the only one I ever replaced a battery for, and since she's left it plugged in 24-7 I haven't replaced it again.

I can't speak for < 2010 or so, but even then 500 nA was common, and half that wasn't rare. I'd expect that we crossed 1 µA around 2003 - 2005, as a very rough guess. But that doesn't mean that every implementation is good, of course; totally possible for a board to do something stupid like have pull-up resistor sinking current continuously on that rail.
> But then you're draining your RTC battery

This is one of the most ridiculous things to care about. And no, a proper hardware doesn't chew up RTC battery even if unplugged for months.

It's very much an avoidable inconvenience to replace. I don't see it as ridiculous at all.

>And no, a proper hardware doesn't chew up RTC battery even if unplugged for months. It in fact takes over a year to completely drain. Perhaps two years. It's inevitable, as CR2032s are not rechargeable and the circuits begins to draw on it less than two minutes after the system is unplugged. Eventually the battery must run out.

> It in fact takes over a year to completely drain. Perhaps two years.

My experience says no.

A'ight.
Well, it is.

I heard about mobos draining the battery like hell, but with my (and not only mine (!)) this is not the norm.

ah if you shutdown your machine by OS, it stays off, and to remotely turn the PC on, I have to turn the smart plug off and on. So no problem with leaving the PC unplugged all the time.
$5 every couple of years sounds worth the convenience.

Might even save that much in idle draw over the lifespan of the battery.

This is such a simple, fantastic idea. I went to enable it but unfortunately it does not appear to be an option available in all BIOSes.
very few motherboard does wake on power
The feature is named auto power on, and is supported quite widely. Search for wake on power might not show positive result.
4 years ago I was active on this solution and I found only server-class machine has that auto-power-on, as of today my laptop and desktop still do not have that, it used to be a server or workstation feature only, did something change? google showed a few servers at the top still.
Curious if this may be due to oem construction?

Every motherboard I've used to build systems with has plenty of options in the firmware, APM being among the most user obvious. Integrated systems like laptops? Not so much.

All RTC/wake up methods are mostly absent since ~2015 in the BIOS of desktop motherboards. You need to configure it in your OS.