1-4 is system board (motherboard) failure. But first try a CMOS memory clear. Power off and remove AC power cable from power supply. Open case and locate the CR2032 coin cell battery on the motherboard. Remove the battery, wait 5 minutes and install a NEW battery.
If this doesn't help then the motherboard is likely toast.
fireberd
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November 17th, 2022 07:00
1-4 is system board (motherboard) failure. But first try a CMOS memory clear. Power off and remove AC power cable from power supply. Open case and locate the CR2032 coin cell battery on the motherboard. Remove the battery, wait 5 minutes and install a NEW battery.
If this doesn't help then the motherboard is likely toast.
redxps630
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15.4K Posts
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November 17th, 2022 08:00
760 service manual shows 1,4 is power connector not connected.
replace battery is good idea for old model. Also check 24/4 pin connectors securely plugged in motherboard. No worries of beeps.
https://dl.dell.com/manuals/all-products/esuprt_desktop/esuprt_optiplex_desktop/optiplex-760_service%20manual_en-us.pdf#page161