Per 780 service manual 1-2 on 3-4 off diagnostic light suggests
A possible expansion card failure has occurred. Determine if a conflict exists by removing an expansion card (not a graphics card) and restarting the computer. If the problem persists, reinstall the card you removed, then remove a different card and restart the computer. Repeat this process for each expansion card installed. If the computer starts normally, troubleshoot the last card removed from the computer for resource conflicts.
redxps630
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April 14th, 2021 12:00
Per 780 service manual 1-2 on 3-4 off diagnostic light suggests
A possible expansion card failure has occurred.
Determine if a conflict exists by removing an expansion card (not a graphics card) and restarting the computer.
If the problem persists, reinstall the card you removed, then remove a different card and restart the computer.
Repeat this process for each expansion card installed. If the computer starts normally, troubleshoot the last card removed from the computer for resource conflicts.