lazydog: My CMOS battery died recently and I have put a new one in.
Prior to this I know that the BIOS was flashed to a newer version, but now I am getting a boot screen that is different-probably a factory default (just a screen displaying the mobo logo and that is it- no checks on system ram, installed componets etc.
The PC boots fine and all is OK, my question is if the CMOS went flat, should the BIOS not remember its previously flashed state? Is there a setting to enable this newer BIOS state or am I going to have to run the gauntlet of flashing again?
I probably will not flash again as currently all seems fine-I just want to know if the flashed state is recoverable within BIOS as I am reluctant to piss about with a system that works OK.
Any advice/lknowledge on this will be most welcome!
The BIOS and the CMOS are completely different things. The battery powers the CMOS memory and clock only and has nothing to do with the BIOS. If your battery dies then all of the system settings stored in the CMOS will be lost. When you put a new battery in, all of your settings will be reset to factory defaults and you'll need to set the date and time as the clock will have reset as well. Normally you'll see an error during first boot after replacing the battery "Warning: CMOS memory checksum error" indicating the memory was corrupted by the dead battery. Subsequent boots should not produce that error assuming the new battery is good.
Your BIOS is stored in an EEPROM which is not affected by the CMOS battery.
lazydog: Thank you for the quick response.
Are you able to tell me then, why does the boot screen differ from the the previously flashed state?
There are settings in the CMOS configuration in many BIOSes which allow configuration of the boot screens, whether a logo is displayed, energy star, quickboot and other settings all of which can alter the way screens look during boot. If you're seeing something different now compared to what you saw previously, then your previous configuration was customized manually either by you or someone else, and the current settings are reset to factory defaults. You'll have to go into your CMOS settings and reconfigure quickboot/etc. to your preference to have it boot up like it did before.
It's also a good idea once you have your CMOS configured the way you like it and working properly, to go screen by screen and take digital pictures of each screen, scrolling options off screen etc. so you have a record of how it is configured in case a battery dies etc. It makes it much easier to reconfigure after problems occur. This is especially true if one has ever had to twiddle CMOS settings to work around hardware problems, BIOS bugs, etc. and the settings to make it work differ from factory defaults. Otherwise one may have to re-troubleshoot all the problems again. I had to do this with some CPU timings and voltages to get one to work before. Not fun. Case where the motherboard manual claimed to support CPU frequencies that did not exist when it was built and then did not actually work with the real hardware with the factory supplied settings. I had to downclock it to get it to work stable. Took forever to sort out. Digital photos are very helpful should it ever lose the settings. :)
