Powering down PC resets BIOS

Pejole2165 said:

Is it a dual BIOS system? Is it possible the BIOS is write protected so doesn't save changes after power down, or could it be loading a default set of settings from the backup BIOS?

Good comment.

Does your system start up then appear to stop and restart again?
I have a Gigabyte board that did that and it was caused by the Main BIOS being corrupt and the Standby BIOS coming on. After reflashing the Main BIOS, the problem stopped.

Pejole2165 said:

Is it a dual BIOS system? Is it possible the BIOS is write protected so doesn't save changes after power down, or could it be loading a default set of settings from the backup BIOS?

Yes, it is dual BIOS and that's actually something to look into. That said, if that was the issue (not saving settings) I'd of known about it long ago as I occasionally shut down the PC for internal maintenance and upgrades. But I will look into the dual BIOS settings just to doublecheck there's no issue there. BTW I just did a BIOS update last night.

pbcopter said:

Does your system start up then appear to stop and restart again?
I have a Gigabyte board that did that and it was caused by the Main BIOS being corrupt and the Standby BIOS coming on. After reflashing the Main BIOS, the problem stopped.

Yeah, I've seen (also read) that happen(s) with a few Gigabyte boards (including this one). No real impact though. Must be a Gigabyte thing as it also happened with my previous Gigabyte motherboards - Z87, Z170, Z270, as well as this Z390 board.

In old gigabytes motherboards with dual bios it is always recommended the 2 bios chips to have the same version flashed.

Kyhi said:

But shutting off the Master Power Supply Switch - you are also shutting off the Standby Power.
Thus Draining the CMOS Battery

I do this on my desktop PC but the CMOS battery still lasts about 3 years

sygnus21 said:

And again, if the battery was draining the clock would also be affected, especially after 3 days. CMOS batteries lasts a long time even without power. But, as I stated earlier, this is a new battery.
.

I've had BIOS problems due to a low battery even when the date is correctly displayed on my Gigabyte motherboard. Did you test the voltage of the new battery which should be c. 3.2V?

It's possible you might have a BIOS corruption which can be fixed by reflashing the BIOS to the latest version.

To put a close on this (for now)….

I never did figure out why the BIOS got reset over a 3 day shutdown period so I'm moving on. In the meantime there was a new BIOS released so I updated it. Also replaced the CMOS battery. BTW about a week later I tested the battery using a volt meter and found it fully charged at 3.1 volts (these are 3 volt batteries) so as I said earlier not a battery drainage issue.

Anyway though the mystery of why the BIOS reset isn't solved, I'll mark this as solved and move on.

Peace:)