Power Supply Multimeter Reading Questions

I am looking for opinion on multimeter readings I am getting for power supply that may or may not be dead. System was found off and subsequently un-bootable after a power outage. Tower was plugged directly into the wall and not a surge protector.

20 pin connector wire readings while plugged into the board:

Purple = 4.96 V
Green = 4.04 V
Gray = 2.1 mV

The yellow wires to the P4 power connector, molex, and other power connectors are reading 1.2 mV each. From what I am reading here some of these are not normal readings, however I am new to using the multimeter so maybe a setting is wrong. It was set to detect DC on auto ranging? If more numbers are needed I can post them. Also makes no difference if the power switch is pushed, nothing changes on the readings. System is a Dell Dimension 9100 with 375 Watt Dell L375P power Supply.


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  1. Best answer
    24 pin connector ?

    Gray wire ( PWR_OK ) should read around 5v
    Yellow wires ( 12v ) should read around 12v

    Sounds like the power outage killed your psu.
  2. Yup looks like a dead power supply probably a power surge this is why we use surge protectors.
  3. +1. 12v is gone.
  4. Dell correct 24pin. Thanks for all the replies. Gonna change out the PSU.
  5. Best answer selected by robomerc.
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