When you try to put an Amperemeter in the circuit between a battery, what does it show?
Some Microamperes are okay, but one of my motherboards has shown some Milliamperes and the battery was empty after one day...

Please give more details.

How fast are the BIOS settings lost? Are they lost even when you push the reset button?
Have you loaded the BIOS or setup defaults after first boot? (This step should at least assure to have a valid CMOS checksum - and should not be forgotten!)
Please try to check the battery circuit with the Amperemeter.

i don't have access to any electrical testing equipment.

i can say that even a ctrl+alt+del will cause the error to pop up again. even going into the BIOS and selecting "load defaults and exit" will get the same result.

The only thing I can think of is that I'm testing these boards without any drives or noncritical cards plugged in... but I only first noticed the CMOS problems when I had one of the machines fully built.

More unpredictable behavior from this project. In my attempts to swap hardware and isolate the issue, the K7VAT+ has gone no-POST on me. This in addition to a few other boards I was cannibalizing. It's also worth mentioning that almost none of my 3 1/2" drives will boot (even though they're perfectly functional in Windows). I've never had this much bad luck reviving PCs, even ones older than this.

buy a humidifier, stop wearing wool sweaters, remove carpet from the room.