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12987 Discussions

CMOS Checksum error


I have a couple of Intel NUCs (from a set of 5 identical ones) that are constantly displaying CMOS checksum errors - and the wrong date. I have done all the normal things: newest BIOS, reset to defaults, secure BIOS reset, CMOS battery replacement, etc - everything suggested in this thread

I have replaced the CMOS battery on one, without resolving the issue, replaced the BIOS chip on the other, without resolving the issue. The CMOS retains all of the other settings (boot order, EFI only boot, etc) it is just the date/time that is the problem and the checksum error.

I have several 5 identical NUCs and only 2 of them have this problem: all the others are fine. Same EFI, same basic configuration.

This is annoying but the machines are still usable - either I permanently have them connected to the power supply or I have to update the time after a longer than usual boot.

Any other ideas?


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Super User

Hi Jack,

We saw in this forum that the new CMOS battery connector was incorrectly wired. So, please check the polarity in the CMOS battery.