I could imagine the CMOS Bios Battery circuits are quite similar on all recent mainboards.
What does it look like and how does it work?
My mainboard started draining the bios battery (an ASRock H55M). I inserted a fresh battery with 3.3v. It only measured 2.9V when I removed it, after the PC had been turned off for about 8 hours. While booting, the BIOS is showing the error message "CMOS Setting Wrong" in combination with "CMOS Date/Time Not Set". My suspicion is, that the battery voltage - while being drained by the mainboard - likely dropped below the 2.9V and caused the error.
So started wondering what could have failed and what this circuit would look like.