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Re: Flashing #3 Diagnostic Light in Optiplex 790

Press F2 and Load BIOS defaults, might be F9 or Alt F -> you shd head beep sound, or Choose Maintenance --> Load Defaults. Go to Maintenance and select Event Log -> Clear event log. Then Esc -> Save and Exit. Even after doing the above step you get the same Alert! errors then The fans inside are not spinning. Try opening the computer and see if all the fans are spinning, if not try to reseat the cables from the Fan to the motherboard.

For the keyboard try using a different USB Port. Check if Num lock Caps lock work when you press the Num lock or Caps lock keys

Mark my answer as resolved if your issue is resolved

Best Regards,

VeejDeej

Endorse me: http://goo.gl/C3567
Dell user
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Re: Flashing #3 Diagnostic Light in Optiplex 790

when keyboard doesnt function at all, how can i press F2. I changed keyboard also. i used ps2 also. but nothing.

regd fans, they spinning very well and i reseted all the cables

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Re: Flashing #3 Diagnostic Light in Optiplex 790

Thanks for your reply

Its mini-tower.

i did same thing but same problem.

Its shows dell logo and F12 boot options.

if i press f12 it gets stuck at the same position.

aotherwise it proceeds to next postion.

the next snapshot is blank screen with blinking screen if i connect PS2 keyboard

and if i connect USB keyboard it shows following, but does nothing

Alert! Air temperature sensor not detected.

Alert! CPU 0 fan failure

Alert! Hard drive fan Failure

Alert! Keyboard initialization failure.

To continue press F1 key

To change setup option press F2 key

To run onboard diagnostic press F5 key

but nothing happens if i press any key. the USB keyboard even doesnt show power.

Regarding the issue time

it was working on a project then they shifted to another project where it doesnt work.

please advise the solution

thanks in advance

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Re: Flashing #3 Diagnostic Light in Optiplex 790

To load BIOS Defaults: Turn off comp, remove power cables, You need 2 move the RTCRST - Jumper pins on the Motherboard from 1-2 to 2-3 and turn on the PC to load defaults. Again turn off PC and put back the Jumper to 1-2 from 2-3.

Mark my answer as resolved if your issue is resolved

Best Regards,

VeejDeej

Endorse me: http://goo.gl/C3567
Dell user
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Re: Flashing #3 Diagnostic Light in Optiplex 790

Hi sajad.wani,

In addition to what 'Veejdeej' suggested, you may also try to re-seat/replace the CMOS battery of your computer and check if it makes any difference. For detailed information on re-seating/ replacing CMOS battery, you may refer to system service manual. Please ensure to follow safety instructions in manual.

@ Veejdeej : Thank you for assisting the customer.

Hope this helps. 

Thanks and regards,
DELL-Chinmay S
#IWork4Dell 

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Re: Flashing #3 Diagnostic Light in Optiplex 790

Thanks Chinmay S,

Is it possible onboard ports like uSB ports, VGA, PS2 ports not working. because i think there is no problem with the processor. Also, when i connect Vga cable to onboard vga port it doesnt display anything. its connected to add-on graphics card. i already re-seated cmos.

is any alternative, if these ports not working,.???

Waiting for your suggestion

Thanks

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Re: Flashing #3 Diagnostic Light in Optiplex 790

Hi sajad.wani,

From the symptoms above, it appears to be an issue with motherboard of your computer. If the system is under warranty, you may private message me the service tag and contact details. Click my username and then click Start Conversation. 

Awaiting your response. 

Thanks and regards,
DELL-Chinmay S
#IWork4Dell 

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Re: Flashing #3 Diagnostic Light in Optiplex 790

Thanks CHinmay S, its not in warranty.

What u suggest, change PC or can be repaired at low cost?

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Re: Flashing #3 Diagnostic Light in Optiplex 790

Hi sajad.wani,

I was just wondering if you have tried replacing the CMOS battery of your computer. If not, it is worth a shot and can be purchased from any local computer store at a very nominal price. You may find detailed instructions from the service manual of computer. Also please ensure that all the connections on motherboard are not loose. If the issue persists after replacing CMOS battery, you may consider replacing the motherboard of your computer. As the system is out of warranty, you may get in touch with either any local technician or Dell support of your region to know the exact cost of the motherboard. 

Hope this helps. Please reply in case you have any further questions. I'll be glad to assist. 

Thanks and regards,
DELL-Chinmay S
#IWork4Dell 

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Re: Flashing #3 Diagnostic Light in Optiplex 790

Hi friend

I am having another problem with Dell optiplex 790 Mini-tower. It showing the same message the previous computer was showing.

But its working when i removed keyboard and mouse and then restarts. when it finsihing the boot-up i plug back the keyboard and mouse.

what is the problem with this pC, how can i fix it.

I am thinking the previous PC also has same problem but may be that also has some additional problem, thats why that one is not working.

Please assist me, may be i can fix both now.

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