Question about recent power outage and PC

Not sure if this was a cure but it worked and not sure why although it came to me to try this.

Came home from work and noticed my power went out while at work. After being home awhile i went to turn on my PC and it did not come on at all no lights nothing.

I checked all breakers in house nothing had tripped. I plugged the PC into another outlet in the house and still no power i proceeded to test the EVGA power supply with the EVGA Detection Tool

and i had power to the power supply then.

Something told me to remove the CMOS battery and once put back in power was restored to the PC and everything is fine.

What else can i expect, was this correct and why?

I am not sure the only thing i see from my surge protector is that part of it called a green zone does not work anymore on it's outlets so i switched this feature off, most likely look into a new one if this can be a cause or future issue with it.

Thanks for the response !

I read about CMOS Battery and only took it out for a few seconds and put it back in and i never made many changes to the BIOS settings except Memory profile which i had to set back to Profile 1.

Surge Protector works fine when i shut off the Green Power switch but i am already looking into purchasing a new one. I have shut off the PC several times and it is fine. You say it fully drains the power when removing this battery i am not fully understanding how that solved my powering on situation by doing so.

It seems a power surge / spike may have corrupted your BIOS settings. Removing the BIOS battery sets the BIOS values to their default settings. I had a similar issue which required the BIOS to be reflashed. A low CMOS battery voltage can also cause a temporary loss of BIOS settings. I would replace the battery (normally a CR2032) if the voltage is below 3V. Note many BIOSs let you save / load your preferred BIOS setting. This is handy - you load the defaults, reboot then set your preferred saved values.

It's unlikely the power surge actually corrupted the OP's BIOS settings. Those are mostly stored on flash memory along with your BIOS image so if the surge corrupted the settings it's likely that the BIOS itself would be corrupted as well and require a full reflash. Also, the BIOS settings don't come into the picture if the system won't power up at all.

My guess is that the surge messed up the power sequencing on the motherboard. In order to boot, the PCH and various other components require the voltage rails and reset signals to rise and fall in a specific order within a certain amount of time. This includes the VccRTC-based signals powered by the coin battery. So if a surge caused some voltage or reset signal to come up unexpectedly, the motherboard may enter a bad state and get stuck. Draining the VccRTC rail resets everything back to 0.

Steve C said:

It seems a power surge / spike may have corrupted your BIOS settings. Removing the BIOS battery sets the BIOS values to their default settings. I had a similar issue which required the BIOS to be reflashed. A low CMOS battery voltage can also cause a temporary loss of BIOS settings. I would replace the battery (normally a CR2032) if the voltage is below 3V. Note many BIOSs let you save / load your preferred BIOS setting. This is handy - you load the defaults, reboot then set your preferred saved values.

Thanks ! BIOS was fine no reflash needed just had to reset some settings back to the way i had it before. As far as the power supply i am using another till i get a better one i am not sure the power outage did it or not as i was not home at the time just noticed one of my clocks was flashing. I do have one of those batteries CR2032 (common battery for many items) noticed when taken out it was that type. Computer is not very old and heard they can last a long time.

You mean this voltage from 3v shown on AIDA64.

VBAT generally refers to the coin battery.

PolarNettles said:

It's unlikely the power surge actually corrupted the OP's BIOS settings. Those are mostly stored on flash memory along with your BIOS image so if the surge corrupted the settings it's likely that the BIOS itself would be corrupted as well and require a full reflash. Also, the BIOS settings don't come into the picture if the system won't power up at all.

My guess is that the surge messed up the power sequencing on the motherboard. In order to boot, the PCH and various other components require the voltage rails and reset signals to rise and fall in a specific order within a certain amount of time. This includes the VccRTC-based signals powered by the coin battery. So if a surge caused some voltage or reset signal to come up unexpectedly, the motherboard may enter a bad state and get stuck. Draining the VccRTC rail resets everything back to 0.

Thanks for the reply ! How about when a PC is unplugged for a period of time say in storage ? As said not sure the outage caused corruption to the surge protector or the surge protector had an issue from the PC being plugged into the Green Power outlets of this surge protector. I had switched off this feature and outlets did work but not to power up the PC till i removed it's battery.

You both know more then i do on this matter i was not sure why this worked but so far glad it did and did not ruin my board, Power Supply or anything else in the process. Will be getting another better Surge Protector

If the PC is unplugged from the wall then the coin battery will be supplying all the RTC power. So the battery will drain faster than if you left the PC plugged in. But on a fresh battery it would still take years for it to fully drain.

Those "green power" sockets are not standardized so their behavior is up to the manufacturer. But they obviously contain additional electronics and probably mechanical relays that can fail during a surge. I doubt that they were directly responsible for the PC not powering up but there's really no way to tell.

"You mean this voltage from 3v shown on AIDA64."

I normally measure the actual CR2032 voltage with a voltmeter and fit a new battery if under 3V. A new battery is normally over 3.2V. Problems with these batteries can cause so much pain and grief so I replace them regularly. I haven't seen a hardware monitor before which reports the CMOS battery voltage. Maybe your motherboard is rare in having a sensor which reports this?