I just read that part and was slightly horrified. It's extremely unlikely that there was anything wrong with the RTC chip. What's much more likely is that the CMOS battery was flat. Usually, that's a CR2032 "button cell" that you can buy for pennies. It takes about 5 minutes to change, most of which is unscrewing and re-closing the case.

At least you have your Pentium. I've still got a bunch of my old code from the 90s and I'd have a very hard time getting any of it to run on a modern PC.