The MIDI Box running Windows 98 Second Edition on an ASUS P55T2P4 board has had a CMOS/RTC issue for about two years, and more recently had issues booting in rare occasion; also had temp corruption within BIOS (would show Unknown CPU for AMD K6-2/500). Date/Time would also revert to Jan 02 1980 at 12:00 AM (and in more recent times, while Windows was running as well), though other CMOS data remained.

The board was pretty much fine before the 24-pin socket replacement, because the first replacement socket was a hack job (clipped 32-pin socket with edge bodge), and the original soldered Dallas CMOS/RTC's battery was long dead.

Procedure for the board:
Change CMOS/RTC to a spare - boot issues were gone though
Reflash BIOS and properly clear CMOS - no real change
Painstakingly remove board from old case and reflow the replacement socket - this seems to have fixed the issues

It's been a little over a week, and the aforementioned issues have not yet returned.