You know that your PC has a real time clock, but how does it work?
Nonvolatile BIOS memory - Wikipedia
HP 430863-001 Motherboard (system board) - Defeatured (DF) - Includes PC Card / ExpressCard assembly - Does not include RTC (Real Time Clock) battery - For nx6315 models - Walmart.com
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Nonvolatile BIOS memory - Wikipedia
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Amazon.com: INTERESTPRINT Solar System with Eight Planets Battery Operated Wall Clock for Living Room Home Office School : Home & Kitchen
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Start System / Deck Clock Battery (R-420-003) – Colorado Time Systems
CMOS Battery – Everything You Need to Know, and How to Replace It; | DESKDECODE.COM
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Replace the Real Time Clock (System) Battery - Sun Server X4-8 Service Manual