problem:

computer starts after ac power is restored (when ac power failure occurs)

even if computer is off.

i went into bios>power>after power failure

and set it to [stay off] f10 & enter.

but it doesn't seem to do anything.

i pulled out power cable and re-plugged and it started again.

i looked again in bios>power>after power failure

and setting was still [stay off]

question:

i don't want it to start after power interruption,

in case no one is home to shut it off.

does anyone know how to fix this?

If you had a power failure your mboard may be damaged.

If you flashed the bios, it usually does not load bios defaults after flashing.
If that's the case, your settings in the bios Setup may not work properly.

You could try this in any case.

Enter the bios Setup, and load Bios Defaults - save settings, reboot. If you flash the bios, you MUST do this (or Clear the CMOS by moving a jumper on the mboard) in order for the bios update to be fully accepted by the mboard - otherwise the contents of the Cmos part of the bios and what you see in the bios Setup may not match the bios version.
Loading Defaults may work in situations where Clear Cmos does not help.
If there is the choice to load Optimal defaults, use that - the bios should automatically use suitable settings for your situation.

You could also try...
Disable Power Management or ACPI support in your bios Setup.

If none of that helps, you can make do...

"i don't want it to start after power interruption, in case no one is home to shut it off."

ATX mboards are always powered in some places, even when the computer is not running, as long as there is live AC being supplied to the PS on the computer.
The solution is simple.
The computer can't boot automatically if you do the following.
If it is plugged into a power bar or UPS, switch off the power bar or UPS when you're not going to be using the computer.
If it is plugged directly into a wall plug, unplug the cord to the computer case when you're not going to be using the computer, or plug it into a power bar or UPS you can switch off instead.

thanks tubesandwires

i think i'll just get into the habit of throwing the black switch in back of psu when not using pc.

OK.

There is something else you could try, but it may not help.
Sometimes problems are caused by you not loading the main chipset drivers for the mboard, but it's usually Shut Down or Restart that doesn't work properly in that case.

Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.

OK.

There is something else you could try, but it may not help.
Sometimes problems are caused by you not loading the main chipset drivers for the mboard, but it's usually Shut Down or Restart that doesn't work properly in that case.
Or, rarely, something to do with the chipset drivers gets corrupted on the hard drive.

Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.

thanks again tubesandwires; you're very informative and helpful.

i had a little time to do everything you suggested including bios flash. process was interrupted because text in terminal read that it did not need update.

but unfortunately, none of these will correct this bug.

so, when i get a little more time i'll get back to this little inconvenience.

You haven't said whether you actually had a power failure.
If you did, it is quite possible your mboard or it's bios is now damaged and that's why you're having this problem.

If you did not have this problem before, that's probably your case, whether you were aware of a power failure or voltage spike or voltage surge or not. The computer DOES NOT have to be running at the time for the mboard or anything connected to it to be damaged - ATX mboards are always powered in some places even when the computer is not running, as long as live AC is being supplied to the PS and the PS is connected to the mboard.

NEVER flash your bios unless you find specific information somewhere, preferably in bios release notes for the update, or in bios release notes for an earlier update that is newer than the bios version on your mboard since later updates normally include all earlier fixes, that doing that will cure a problem you are having fr sure. 99.9% of the time flashing the bios will NOT help if you find no such info.
You are taking a big risk when you flash your bios - if the flash fails, and/or the flash chip physically fails while flashing (this is COMMON - these cheap flash chips can only be flashed an unpredictable small number of times), you will have a mboard that will not boot.
If the flash fails, but the flash chip is physically okay, you can follow a specific Recovery procedure, according to the brand of your bios.
If the flash chip physically fails you will have a dead mboard until that is fixed, and you may need to obtain a new flash chip, already flashed.

Going by your specs in your 1st post, your mboard is new enough that it is extremely unlikely the bios would have a bug that causes this problem.
If you were not having this problem previously, you had no justification for trying to flash the bios.