Or are they held in some other volatile memory chip on the motherboard?
On older boards it's actually sometimes flashed in the EEPROM, mostly those settings are stored in volatile memory in the chipset or the RTC module though.
Interesting. Because this PC I have reports a bad RTC during diagnostics. And it won't save cmos settings. Could be the same chip causing both problems?
I always thought the settings were saved in the RTC, which would explain why settings are not saved if you have a faulty RTC or dead battery.
See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.
debs3759 wrote on 2020-08-11, 00:30:I always thought the settings were saved in the RTC, which would explain why settings are not saved if you have a faulty RTC or dead battery.
I've been chasing a problem where with a good battery it still won't save settings. Sounds like the RTC might be bad afterall.
kingcake wrote on 2020-08-11, 01:37:debs3759 wrote on 2020-08-11, 00:30:I always thought the settings were saved in the RTC, which would explain why settings are not saved if you have a faulty RTC or dead battery.
I've been chasing a problem where with a good battery it still won't save settings. Sounds like the RTC might be bad afterall.
Check it with the motherboard out of the case - if the motherboard is getting grounded somewhere, it will lose the CMOS setting as soon as it's powered off. And make sure the battery contacts are clean.
After watching many YouTube videos about older computer hardware, YouTube began recommending videos about trains - are they trying to tell me something?
Repo Man11 wrote on 2020-08-11, 01:56:kingcake wrote on 2020-08-11, 01:37:debs3759 wrote on 2020-08-11, 00:30:I always thought the settings were saved in the RTC, which would explain why settings are not saved if you have a faulty RTC or dead battery.
I've been chasing a problem where with a good battery it still won't save settings. Sounds like the RTC might be bad afterall.
Check it with the motherboard out of the case - if the motherboard is getting grounded somewhere, it will lose the CMOS setting as soon as it's powered off. And make sure the battery contacts are clean.
no battery contacts, this is an old 386 board with a soldered battery. I replaced it already but it still loses settings. In or out of the case.
Aswering your question in a general way, I would say "it depends in the board and the manufacturer". Mobile and some embedded platforms (notably the ones equipped with OEM (IBM, Toshiba, HP, Compaq, etc), Phoenix, and SystemSoft BIOSes) traditionally store part of the NVRAM data in EEPROM since ever, mostly security data like HDD and Supervisor/User key hashes. Also, Pentium+ PCI/PnP boards store and update their ESCD tables in a partition area of the main BIOS chip or Firmware hub, in Intel boards case. That's why you see some warnings/errors in BIOS BBS post stage if you have enabled chip write protect. Finally, some boards would have an option to attempt to save a copy of your defaults to EEPROM, and use them in case of corrupted RTC values.
That makes sense. I remember boards having the "save settings as default" option.
