After some research though, came across this nice blog entry from last year that solved my problem completely. For about $5 (for two batteries actually, only needed one, but now I have an extra) at my local Food Lion. So if you're having this issue, even if you don't have an ASUS MB, try this first if your MB is more than 3 years old.
You can read the whole blog post here, the entire post copied and pasted here, so you don't need to go to the blog! (Just adding that so humblegunner doesn't get on me for blog pimping hehe). It's not even my blog.
Again, just sharing this for anyone having the same problem. Definitely worth a try at least, before you run out and spend a couple hundred bucks on a new motherboard or worse a thousand on a new computer. I'd just verify that your motherboard uses the same type of battery (CR2032) described here, probably does it seems they are pretty standard but just in case before you waste the $5.
Maybe everyone else here knew of this solution already, if so great. I just thought maybe someone could benefit. You can find helpful videos online describing how to change the battery, or consult your motherboard manual.
The only thing you'll need to do after doing this is reset the internal clock time since removing the old battery will of course wipe that. But that's pretty easy, my BIOS prompted me to do that when I restarted the computer.
I always turn off the chassis intrusion feature from the BIOS, myself. In my experience, a weak battery either throws its own error (right approach) or the clock suddenly doesn’t keep good time, at least on boot.
To be honest the CMOS battery dying is an indication you’ve had the board a really long time ;-). Asus Maximus hero used to be an awesome gaming motherboard brand. The newer ones all seem to have cheaper VRM’s that are noisy.
Had similar problems with an old computer...finally got tired of having to tell the BIOS to ignore the errors so it would boot up and changed the battery - ran good for another couple years before the HD finally did what old HDs do...
Ha...and I thought this thread was about the Tesla battery exploding and the door handles locked resulting in a carbonized driver.