Here is the link to the manual for your computer: http://support.dell.com/support/edocs/systems/dim3100/en/sm/adtshoot.htm#wp1124612 The answer depends on whether your power button light is a solid yellow or flashing yellow. Likely that you could need a new power supply. Check the diagnostic lights (the numbers that are lit up on the front panel) and follow the manual. Dell support can assist you with locating the necessary part(s).
Answers & Comments
I removed the connector at "J5J3 pswrd."
this is the blue thing between the battery and the card slot.
i tried everything else such as new M/B battery. remove/change ram. take out extra card, etc.
I just fixed my dell dimension 3100 by doing this.
Here is the link to the manual for your computer: http://support.dell.com/support/edocs/systems/dim3100/en/sm/adtshoot.htm#wp1124612
The answer depends on whether your power button light is a solid yellow or flashing yellow. Likely that you could need a new power supply. Check the diagnostic lights (the numbers that are lit up on the front panel) and follow the manual. Dell support can assist you with locating the necessary part(s).