Unsolved
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May 10th, 2025 23:52
Unusual behavior when powering on
Dell Optiplex 790 SFF manufactured in 2011
When booting up the computer, it comes on, then turns off after a few seconds, then comes back on again after a few more seconds. However, the boot process does not complete and diagnostic amber lights 1 2 3 remain on (manual suggest a possible coin cell battery failure has occurred). Powering down and restarting exhibits the same initial on - off - on again behavior, but this second time the boot process completes successfully.
I replaced the CMOS battery, but this same behavior still occurs. As long as I get the system up and running with that second attempt, I can live with this. But I am curious to learn what the cause might be.
Thank you in advance for your thoughts.
Regards,
John
JOcean
9 Legend
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12.6K Posts
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May 11th, 2025 00:59
When you replace the battery make sure to remove the battery for 15 minutes before installing a brand new recently purchased battery.
jhcarver
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May 11th, 2025 01:40
I replaced the new battery in about 1 minute with the computer powered down. I'll repeat the procedure and leave the CMOS socket open for at least 15 minutes as you've suggested.
jhcarver
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June 29th, 2025 11:00
I'm going to replace the coin cell battery again today. I will leave the CMOS socket open for at least 15 minutes as you've suggested. I am curious to know why that is necessary.