Hi, OP, The title of the thread says blinking blue light. The power light on Dells is a diagnostic tool. Here's a snip from your manual..
http://support.dell.com/support/edocs/systems/xlob/dtg/en/en_dtg.pdf
Note the: "If the power light is blinking amber, the computer is receiving electrical
power, but an internal power problem may exist."
The power button light located on the front of the computer illuminates and
blinks or remains solid to indicate different states:
• If the power light is blue and the computer is not responding, see the
Service Manual for your computer.
NOTE: On certain systems the power light is green.
• If the power light is blinking blue, the computer is in standby mode. Press
a key on the keyboard, move the mouse, or press the power button to
resume normal operation.
NOTE: On certain systems the power light is green.
• If the power light is off, the computer is either turned off or is not
receiving power.
– Reseat the power cable into both the power connector on the back of
the computer and the electrical outlet.
– If the computer is plugged into a power strip, ensure that the power
strip is plugged into an electrical outlet and that the power strip is
turned on.
Dell Support
Utility
Use this support utility for self-support information, software
updates, and health scans of your computing environment.
power button
274 Troubleshooting
– Replace power protection devices, power strips, and power extension
cables with similar products in known working condition to verify that
the computer turns on properly.
– Ensure that the electrical outlet is working by testing it with another
device, such as a lamp.
– Ensure that the main power cable and front panel cable are securely
connected to the system board (see the Service Manual for your
computer).
• If the power light is blinking amber, the computer is receiving electrical
power, but an internal power problem may exist.
– Ensure that the voltage selection switch is set to match the AC power
at your location, if applicable.
– Ensure that the processor power cable is securely connected to the
system board (see the Service Manual for your computer).
• If the power light is steady amber, a device may be malfunctioning or
incorrectly installed.
– Remove and then reinstall the memory modules (see the
documentation shipped with your computer).
– Remove and then reinstall any cards (see the documentation shipped
with your computer).
• Eliminate interference. Some possible causes of interference are:
– Power, keyboard, and mouse extension cables
– Too many devices on a power strip
– Multiple power strips connected to the same electrical outlet
Diagnostic Lights for Desktop Computers
Some desktop computers have lights labeled with numbers on the front
panel. When the computer starts normally, the lights flash, and then turn off.
If the computer malfunctions, the sequence of the lights can be used to help
identify the problem.