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Optiplex 790 MT power button
when power button is pressed, the chassis and CPU heatsink fans turn on immediately for 1-2 sec, then both fans turn off and pause for 2-3 sec, then both on again and motherboard boots with Dell logo showing up on monitor.
Why is the motherboard thinking for a few seconds before booting? Why do fans turn on, off for 2-3 sec, then on again?
Once booted, system works perfectly without issue.
savvy2
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2547 Posts
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Posted January 19th, 2020 15:00
the RTC coin cell does not last forever.
2011 PC 9 years old battery life is 5-7 years, (some go longer under ideal conditions but this is FIRST.)
the service manual at dell.com 790MT shows where it is. on the MOBO
I have a 790, and know it well. (it's my lab test , torture machine)
not saying that is the only problem there are many possible, the above is $1 fix,.
see the strip down test, that finds them all, yes, ALL.
ATX Power spec is a 1 second rule (wiki it) and if the PC overloads the PSU the PSU shuts off in 1 second or less. by DESIGN. (stops the fire/smoke thing, that too by law, UL , NECA, etc.)