How can a dead CMOS battery interfere with USB controller startup?

Question

Iron

Sometimes in my free time, I fix my friends' computers. Recently I came across one very interesting case: a girl on a rather old machine periodically fell off all USB devices for no apparent reason. I was very lazy to deal with this PC at that moment, therefore, at the first start, after making sure that the USB keyboard and mouse were working as they should, I referred to the burnt south bridge and advised me to look for a new motherboard (especially since it was really impossible to touch the chip - - he was so hot.
After some time, interest again pulled to see what could be wrong there, and this time the USB keyboard did not work anymore. HOWEVER, after a reset by closing the Reset contacts, the keyboard blinked its LEDs and started working!
In short, after 40 minutes of constant reboots, it was found that USB fell off after a cold power reset, and on the first start after such a shutdown, POST spends 10 seconds on the line "Initializing USB controllers ...". When restarting without power loss, the initialization of the controller occurs instantly and everything works fine until the next power loss.
At the same time, the CMOS battery was discharged on the motherboard. After replacing with a known working battery, the malfunction could not be reproduced, and for 2 months now this girl has never complained.
Attention to the question: how to explain this behavior? What does a CMOS battery have to do with a failed controller initialization? The motherboard, if I'm not mistaken, was this one: M2N32-SLI Deluxe.

Answer 1

A discharged battery in general can randomly affect both the entire car and its individual parts. In my practice, there have been many cases, from refusing to turn on at all, to the fact that the operation of the ATA IDE controller with a completely serviceable disk was buggy. It is impossible to predict where the problem with the battery will come out, for this reason, when I take it for repair, the first thing I do is check the condition of the battery, along with cleaning it from dust and juggling all the cords.

Answer 2

1/ If the BIOS does not work properly, it can negatively affect a lot
2/ "I was very lazy" and "advised me to look for a new motherboard" = very professional ;-(