Hello everyone, I have an odd problem with my 690. In BIOS it always says that the CMOS battery is low, and it always says the system has shut down due to a "thermal event" (although it has NEVER shut off due to overheating). It also NEVER saves ANY CMOS BIOS information, regardless of what CMOS battery is in it. I've tested 3 batteries and they all do the same thing. BIOS says the battery is low, can't save settings, etc. It even does this if there is no battery in it at all (reporting low battery and thermal shutoff). I am guessing this could be a capacitor issue, or is it something else?
I found information that it could be a couple of things. First, it may be a malware on your computer. Here is a solution that worked for one user, not sure if it's exactly your issue, or even if it will work for you, but it's worth a try: http://dell.to/2xg4evh
Second, it may be that the motherboard may need to be replaced. Before deciding that, try a backup of your system and a complete OS reinstall first, then start looking for motherboards if that's not working.
Third, you can contact Dell Out of Warranty Support if you don't have the time or the desire to work on it yourself. http://dell.to/2xg4f2j