Swapped out the PSU with a known working one, upon plugging in the pwr cable, the pwr button back-lit GREEN and there were no longer any numeric codes blinking. Initiated a boot cycle but INTO Setup, confirmed drives are showing up, memory as well. Booted again, F12, into on-board diags, and everything passes the quick test. Might suggest the blinking 1 & 3 could have been residual effect from the failed PSU to begin with. Looks like blinking Amber pwr button supersedes the diagnostic numeric codes, at least until you remedy the power supply unit. Answer from Towster on dell.com
Top answer 1 of 7
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Swapped out the PSU with a known working one, upon plugging in the pwr cable, the pwr button back-lit GREEN and there were no longer any numeric codes blinking. Initiated a boot cycle but INTO Setup, confirmed drives are showing up, memory as well. Booted again, F12, into on-board diags, and everything passes the quick test. Might suggest the blinking 1 & 3 could have been residual effect from the failed PSU to begin with. Looks like blinking Amber pwr button supersedes the diagnostic numeric codes, at least until you remedy the power supply unit.
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Dell Diagnostic Indicators According to the diagnostic indicators, lights 1 & 3 indicate a RAM problem. Blinking orange power light indicates a failing or failed PSU. I had a RAM problem with my 755 last year. Lights 1 & 3 lit up and power button light was a steady orange. How's the CMOS battery? A low battery can cause all sorts of bizarre problems. Replacement to rule it out is cheap. I'd try reseating RAM chips one at time, starting with no RAM. See if the error repeats. Remember to unplug power cord in between reaseating chips. If the error remains unchanged, I'd have to suspect the PSU. One of our other Rockstars or experts might chime in too. The light combo you had I don't believe is normally one seen together. You may also use the 'Get Help Now' option at the bottom right to chat with a Dell technician right away.
Dell
dell.com › support › kbdoc › en-us › 000126021 › a-reference-guide-to-the-dell-optiplex-diagnostic-indicators
A Reference Guide to the Dell OptiPlex Diagnostic Indicators | Dell US
With this series, the diagnostic LEDs changed to include a combination of the Power button LED state and the diagnostic LED indicators. The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit.
Optiplex 780 DT green power light, lights 1,3,4
Hello, I just got a free dell optiplex 780 dt that powers on but there's no video output and it is only showing a green power light and 1,3,4 diagnostic lights. Repasted cpu and cleaned ram slots. ... More on dell.com
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February 27, 2024Optiplex 780 will not boot: 1 & 3 lights blinking & Power Button Blinking Amber
Dell Optiplex 780 mini tower. Computer was working okay yesterday, no changes were made or work done on the box. Walked into the office this morning and saw: Computer seemed to be powering/shutting down in intervals of about 1 second. I pulled the power cord and plugged back in. Attempted to... More on forums.tomshardware.com
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November 5, 2013Dell 780 SFF Problem: Diagnostic lights 1-2-3 lit, two beeps
I have searched for similar problems as the one listed, and I have found people who have asked the same problem. The issue I had was that the people looking for help did not report back about wheth... More on dell.com
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August 18, 2014Hi got an optiplex 780 that won’t boot up after hitting on button. Boss wants to get rid of it but for learning reasons how could I fix it ?
I'm sure if you google "Dell optiplex 780 diagnostic lights" you'll find what it's trying to tell you. More on reddit.com
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December 25, 2022Videos
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Solve Dell Lights 3 on an Optiplex 780 Error Code Memory Bad |By ...
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FIXED! Dell Optiplex Amber Light Issue [English] - YouTube
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Dell Optiplex 745 Error code 3, 4 repair - YouTube
Dell
dl.dell.com › manuals › all-products › esuprt_desktop › esuprt_optiplex_desktop › optiplex-780_service manual3_en-us.pdf pdf
Dell OptiPlex 780 Service Manual - Small Form Factor ...
To help troubleshoot a problem, your computer has four lights labeled 1, 2, 3, and 4 on the bank panel.
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From A Reference Guide to the Dell OptiPlex Diagnostic Indicators: JOcean is spot on. Did you already replace the size 2032 CMOS battery? You may also want to try a BIOS reset via the jumper method. How do you know the RAM is good, did it come from a working system, or tested in a working system? If you pull the RAM and power on, do the error lights stay the same? If not, reseat RAM one at a time until 1,3,4 error repeats. CPU isn't ruled out yet. From what you tried already with JOcean's suggestions, if my suggestions don't change anything, the MB may be a frozen brick.
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Are the LEDs amber coloured? If so then it could mean a bad MB. Disconnect everything from the MB (any cards, drives, etc.) and only have power from the PSU to the MB. If the system powers up then reconnect everything one at a time until the error occurs. The last item connected is the problem. Now if it does not power up with everything disconnected then it starts to look like a MB. You could also pull the CMOS battery for a few minutes then reinstall and try again. Actually for a 13 year old system I would suggest replacing that battery (CR2032).
Tom's Hardware Forum
forums.tomshardware.com › home › prebuilt & enterprise
Optiplex 780 will not boot: 1 & 3 lights blinking & Power Button Blinking Amber | Tom's Hardware Forum
November 5, 2013 - Just changed mine and it worked like a charm I've the ssame problem,blinking Amber light and 1&3 light codes. So the only way is to change the SMPS? If yes can you suggest one or should i replace with the same thing? Hello, My Dell Optiplex 780 system unit diagnostics light blinks for 7 times and the system does power.
Dell
dell.com › dell community › desktops › locked topics – desktops general
Dell Optiplex 780 MiniTower, power light flashes amber diagnostic lights 1 & 3 flash | DELL Technologies
November 7, 2016 - I believe you're correct. After replacing the BIOS battery I now get lights 3&4 flashing, still the amber power light. Playing with the power supply test button and pressing the power button at the same time it finally comes up.
Dell
dell.com › dell community › desktops › locked topics – desktops general
Dell Optiplex 780 Error Messages/Diagnostic Codes Power Button and then 1 and 3 number lights flash | DELL Technologies
August 30, 2017 - My computer was working fine until the other day when the computer power button flashes and then the number 1 and 3 lights flash thereafter simultaneously. Although I've researched the diagnostic c...
ManualsLib
manualslib.com › brands › dell manuals › desktop › optiplex 780 › service manual
Diagnostic Lights - Dell OptiPlex 780 Service Manual [Page 15] | ManualsLib
May 9, 2014 - Dell OptiPlex 780 Manual Online: Diagnostic Lights. To help troubleshoot a problem, your computer has four lights labeled 1, 2, 3, and 4 on the bank panel. When the computer starts normally, the lights flash before turning off.
Dell
dell.com › dell community › desktops › locked topics – desktops general
Dell 780 SFF Problem: Diagnostic lights 1-2-3 lit, two beeps | DELL Technologies
August 18, 2014 - A 7B stop would mean the SATA Operation setting in BIOS is incorrect. For Win 7, it probably should be set to RAID Autodetect / AHCI. Incorrect SATA Operation BIOS setting would be consistent with the diagnostic 1-2-3 you get.
JustAnswer
justanswer.com › computer › fahk3-power-button-flashing-amber-green-lights.html
Troubleshooting Dell Optiplex Diagnostic Lights and Flashing Orange Light Issues
OptiPlex 780 may show amber power button flashing and fail to display video output on monitors. Amber power button flashing with green lights on LEDs 1 and 3 indicates hardware POST errors. First, disconnect all peripherals and try powering on.
Reddit
reddit.com › r/dell › hi got an optiplex 780 that won’t boot up after hitting on button. boss wants to get rid of it but for learning reasons how could i fix it ?
r/Dell on Reddit: Hi got an optiplex 780 that won’t boot up after hitting on button. Boss wants to get rid of it but for learning reasons how could I fix it ?
December 25, 2022 - https://www.dell.com/support/kbdoc/en-uk/000126021/a-reference-guide-to-the-dell-optiplex-diagnostic-indicators#2009_to_2012 · 1,3 and blinking orange: A possible system board, power supply, or device failure has occurred.
Dell
dell.com › support › kbdoc › en-uk › 000126021 › a-reference-guide-to-the-dell-optiplex-diagnostic-indicators
A Reference Guide to the Dell OptiPlex Diagnostic Indicators | Dell UK
With this series, the diagnostic LEDs changed to include a combination of the Power button LED state and the diagnostic LED indicators. The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit.
Newegg
images10.newegg.com › UploadFilesForNewegg › itemintelligence › DELL › 82b467d5_215c_4ca8_8bc5_d9caba3fadee1476183183094.pdf pdf
Dell OptiPlex 780 USFF Service Manual
To help troubleshoot a problem, your computer has four lights labeled 1, 2, 3, and 4 on the bank panel.
Dell
dell.com › dell community › desktops › optiplex desktops
Optiplex 780 SFF blinking 1,3 without the power light and 3 on power button press | DELL Technologies
April 29, 2025 - For the diagnostics light, code 1, 3 indicates system memory issue. See screengrab from service manual below. Besides replacing a fresh coin cell battery, I suggest to clear your system NVRAM by reset CMOS via jumper.
Dell
dell.com › dell community › desktops › optiplex desktops
Optiplex 780 1 & 3 lights | DELL Technologies
May 22, 2020 - May 22nd, 2020 18:00 · Orange light on the MB -.that part in normal - means it has power. Don't know if you already tried reseating the RAM. The size 2032 CMOS battery lasts around 5 yrs. The 780 goes back to 2010. So, either way, I'd replace the battery. That's the first thing I had to do with one refurb Optiplex I bought. Fireberd is right about error codes 1 & 3. Dell Diagnostic Indicators ·
Reddit
reddit.com › r/techsupport › dell optiplex 780 dt powers on with green power light, 1,3,4 diagnostic lights
r/techsupport on Reddit: Dell Optiplex 780 dt powers on with green power light, 1,3,4 diagnostic lights
February 25, 2024 - I just got a free dell optiplex 780 that powers on but doesn't output video. Green power light, 1,3,4 diagnostic lights. I have a "pc analyzer" pci test card and that only shows error 0002 or 00C4. Tried it with working ram and known good cpu. Power supply has good voltage.
Dell
dell.com › dell community › desktops › optiplex desktops
optiplex 780 Desktop power cut out lights 1, 2, 3, and amber(identified as screen connection) | DELL Technologies
August 5, 2021 - Hello, I had an error with a optiplex 780 lights, 1, 2, 3 and the amber sort of sequence of lights, 1,2 refers to a problem with some component. The system simply shuts down. What solved this, was ...
ManualsDir
manualsdir.com › directory › brands › dell manuals › computers › optiplex 780
Diagnostic lights | Dell OptiPlex 780 User Manual | Page 24 / 73
To help troubleshoot a problem, your computer has four lights labeled 1, 2, 3, and 4 on the bank panel. When the · computer starts normally, the lights flash before turning off. If the computer malfunctions, the sequence of the lights help ...
Dell
dell.com › dell community › desktops › optiplex desktops
Optiplex 780 Lights blinking 2 3 4 amber light | DELL Technologies
March 1, 2021 - Last ditch effort: With all external peripherals disconnected (keyboard, mouse, monitor, etc.) power on and see if 2,3,4 repeats. If not, plug things back in one by one until it repeats when powering on.
Dell
dell.com › dell community › desktops › optiplex desktops
Optiplex 780 amber light blinking 1 and 3 amber power light | DELL Technologies
January 16, 2021 - There's 2 ways to reset CMOS/BIOS/NVRAM. Remove the 2-pin CMOS jumper is what I think you're referring to. However, we don't need to worry about that because the other way to do it is remove the battery for 10 min. Replace with a new one (size 2032).