You might wonder why I am posting this. Please read on.....yesterday I boot up, to be confronted with 'cmos checksum error'...blah blah. Now I was able (after half an hour of worry) to sort this out. Without a proper Rom bios my PC kept trying to boot from the second hard drive (IDE) not the first (SATA) and no amount of fiddling with the bios could get round the problem. BUT by a mere quirk, I found I had a floppy disc with the original ROM bios on it - a backup which you are reminded to take when you attempt a bios flash update, and how I blessed it. A quick reflash with the original Rom and I am back in business again. pretty lucky really, and I dont suppose more than 0.01% of PC users ever take a backup of their Rom bios? Well, do it. This PC is just about 4 years old, and the motherboard battery should not be done for yet, but maybe it is, and without that backup, there is no way to recover a working PC.