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4 Germanium

Re: Flashing #3 Diagnostic Light in Optiplex 790

Hi sajad.wani,

You may try to reseat the CMOS battery from the computer and see if it helps. For detailed information on same, you may refer to system service manual: http://bit.ly/XnP4vD

Please ensure to follow safety instructions in manual and share the findings. 

Thanks and regards,
DELL-Chinmay S
#IWork4Dell 

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RE: Flashing #3 Diagnostic Light in Optiplex 790

Hi. Sorry for the very late response to my post... I found a video in youtube and I think this may solve the issue... The culprit was the power button not the CPU or the motherboard.. See video below. 

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RE: Flashing #3 Diagnostic Light in Optiplex 790

I was messing around with my PC trying different video adapters such as Display Port->VGA and other adapters i had to make it work. Upon swapping out my original display port to display port connection is when i had the blinking orange 3. I reverted back to my display port to display port connection and the PC powered on just fine. So there i can rightfully assume that this is a problem with your video adapter. Try switching to VGA or DVI or Display port without any adapters and hopefully you find a solution in that.