15 posts in this topic

Posted

Hi guys,

 

I'm something I haven't been for a while: Bemused, confused and confuzzled.

 

You see, 10 minutes ago I experienced a very minor power cut caused by a switch flicking in the meter.

 

Anyway, of course all went quiet in my room (except for my noisy archaic laptop fan). The powerhouse of a computer under my desk fizzled out a second later, its previously glowing power light all but invisible.

 

So, a few minutes later, power is restored.

 

Of course, everything has reset and, there is no doubt about it, the computer Had No Power for a good 3 minutes.

 

So I press the power button, immensely annoyed as I realize I have just lost changes I made to a number of backend files on my new under-development blog/website.

 

Imagine my surprise (and delight) then when upon signing back in everything is still open - exactly how it was before the power cut! Just like the computer had gone to sleep... although it had actually been without power for a good few minutes.

 

So how did this happen? Does Windows save current state or something when power is lost? Seems unlikely. And, no, it is not connected to any sort of backup battery, UPS unit or even fancy extension cable... it is connected directly to the wall socket. So please, anyone who can shed some light on this and explain how this incredibly useful feature actually works, please can you explain it?

 

Thanks in advance,

Ilmiont

 

PS: Some details on the computer, although I doubt its related:

Motherboard - ASRock FM2A88X Extreme4+

CPU - AMD A10-7850K

PSU - Corsair CX500M

Storage setup - 160Gb Samsung 840 EVO SSD/320Gb internal Western Digital Caviar HDD (also other external drives :))

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Posted

Probably went in to standby mode.  I forced a PC off earlier by holding down the power.  When I turned it back on, it said "Resuming Windows" and everything I had open, was still open and I was still logged in.

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Posted

you're probably on windows 8/8.1

 

this is was one of the better improvements the MS made

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Posted

you're probably on windows 8/8.1

 

this is was one of the better improvements the MS made

 

So windows 8/8.1 constantly write ram to disk?? I only found this:

 

Windows 8 Sleep Mode

Windows 8's Sleep saves your data to RAM and then switches to minimal power mode.  There is a 4 second delay as Windows 8 switches back to normal power mode.  In the event of a power failure you would lose any unsaved data which is stored in RAM (memory).  At this point you will probably have to type in your password to resume after sleep; fortunately, 'Require a password on wakeup' is another configurable setting from the task list menu.

 

 

 

So how did this happen? Does Windows save current state or something when power is lost? Seems unlikely. And, no, it is not connected to any sort of backup battery, UPS unit or even fancy extension cable... it is connected directly to the wall socket. So please, anyone who can shed some light on this and explain how this incredibly useful feature actually works, please can you explain it?

 

Thanks in advance,

Ilmiont

 

PS: Some details on the computer, although I doubt its related:

Motherboard - ASRock FM2A88X Extreme4+

CPU - AMD A10-7850K

PSU - Corsair CX500M

Storage setup - 160Gb Samsung 840 EVO SSD/320Gb internal Western Digital Caviar HDD (also other external drives :))

 

The computer needs to copy the contents of the RAM, or keep power to the RAM to restore where you left off. generally in a power outage there isn't enough time to even detect power being removed, much less dump the GB's of ram data to disk. I don't get whats going on here but if you are doing that kind of work I'd invest in a UPS with USB control to automatically power off your system in the event of a power failure. If I had to venture a guess, it went to sleep JUST before the power went out.

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Posted

So windows 8/8.1 constantly write ram to disk??

We used to call that a 'pagefile'. ;)
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Posted

Very interesting, and standby still needs power, RAM certainly can't be kept alive for 3 minutes with no power. and hibernate couldn't possibly have been instant either.

 

 

... unless a power supply is actually capable of keeping reserve power and powering the RAM during that outage. Wouldn't surprise me if it did, standby draws about 1-5 watts, which is very low.

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Posted

ever notice sometimes in a power supply that when you unplug it, the LED stays on for a little bit of time? ram was probably still running off the caps. caps also had enough juice for the system to detect the power loss/low power and go into deep sleep.

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Posted

I'm surprised by this, if you had no UPS, there is no way it was sleep mode. And it takes quite a few seconds to go to hibernate mode, which you don't have time to do when a power outage occur.

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Posted

We used to call that a 'pagefile'. ;)

 

I know, and we used to need one for anything to work. Apparently now RAM is so advanced it just never loses its data. 

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Posted

Is it that big of a deal?

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Posted

Were you working on your laptop or desktop at the time?

 

Is your desktop set to sleep automatically after a time period?

 

Is hybrid sleep enabled on your desktop?

 

In BIOS settings; which suspend type is set: S1 (Power on Suspend (POS)) or S3 (Suspend to RAM (STR))?

 

 

My guess is your desktop was already in the hybrid sleep state but with fans still spinning (probably because it's set to S1 state) when the power was cut.

 

If that's not the case, then I have no other theories.

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Posted

If the power wasn't fully cut, and you have a good earth ground, you may still get some voltage between either leg and earth, and that may have been enough power to allow the computer to suspend to RAM, or even hibernate, but might not enough to operate a monitor.

To elaborate, in the UK, you have 220/240v power, correct? So that is 220v between the main 'legs', or pins on the outlet, and 110-120v between either 'pin' and the ground / earth pin. So the PSU may have been able to source enough current to put the computer in a lower power mode, even hibernate but not enough to run things proper.

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Posted

"Just like the computer had gone to sleep."

This is most obvious solution - were you actively working on the desktop when you lost power? Or is more likely that the box had to gone to sleep while you were not using it, etc.

" it is not connected to any sort of backup battery, UPS "

What is wrong with you? I would suggest you go to the store or order online today a UPS for your computer and electronic equipment. Modem/Router/Switches/ETC..

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Posted

It was a miracle.

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Posted

If the computer was not in sleep mode I can't see how else everything resumed as if the power outage never happened.

 

Do as Budman said and go get yourself at least one UPS for that computer and your modem/router. I've seen many computers fried from the ethernet port because the cheap routers and modems can't handle even moderate surges.

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