Solved Dell Optiplex 790 Has Died

April 6, 2018 at 06:55:27
Specs: Windows 10 Professional
I think the motherboard on my Dell OptiPlex 790 has died. The 1, 2, 3 lights came on. I cannot boot up the computer. I changed the CMOS battery and I re-seated the RAM but nothing happened. I want to know if it's truly gone or if there is something else I could do.

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✔ Best Answer
April 9, 2018 at 07:24:32
If you see nothing on your screen, try swapping out the monitor and monitor cable from another computer to confirm that it is not just the monitor or cable that is bad.
Try any bootable CD/DVD like Live Linux, Seatools from Seagate (hard drive test), Memtest86 (memory test), etc. to see if it will boot from another source.
Try unplugging the hard drive as suggested earlier to see if it will boot to BIOS settings or at least show 'no boot drive' on screen.

You have to be a little bit crazy to keep you from going insane.



#1
April 6, 2018 at 07:22:46
So, describe what, if anything happens when you attempt booting the computer.

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#2
April 6, 2018 at 08:10:54
Nothing happens at all. It runs the POST and then the 1, 2, 3 lights come on and stay on.

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#3
April 6, 2018 at 09:27:56
Diagnostic LED 1-2-3 generally means you have a bad CMOS battery. Are you sure you installed it correctly? Did you unplug the power cord & hold the power button for approx 20 seconds to clear any residual charge before swapping batteries?

http://www.dell.com/support/article...

EDIT: I see you have two posts & two different model numbers (780 & 790). Was that a typo or are you working on 2 different machines?

message edited by riider


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Related Solutions

#4
April 6, 2018 at 09:30:01
Please don't double post - one might get deleted. You can always add another input if you have more information.

If it's a hardware fault there are other possibilities such as the hard disk or the power unit.

Try booting it using a LIVE LINUX CD/DVD (they can be downloaded) because that will help prove things. You just boot Linux with the disk in the drive and when you have finished it goes back to Windows. Puppy Linux is quite good for this but do not INSTALL it - run it from the CD/DVD. You will need to get into BIOS to set the disk drive ahead of the hard drive. Can you get into BIOS?

Always pop back and let us know the outcome - thanks


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#5
April 6, 2018 at 09:50:22
I unplugged the power cord but I didn't hold the power button.

I am working on 2 different machines.

I'm not able to get into BIOS right now. Nothing comes up on the screen at all.


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#6
April 6, 2018 at 11:03:52
Try renewing the cmos battery and ensure you install it the right way round.

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#7
April 6, 2018 at 11:37:11
I unplugged everything, held the power button for 20 seconds, and re-installed the CMOS battery. I plugged everything back in and turned it on. It started up, then it powered itself down for about 5 seconds, then came back up and the 1, 2, 3 lights stayed lit.

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#8
April 6, 2018 at 13:03:47
"It started up, then it powered itself down for about 5 seconds"

For about 5 secs or after about 5 secs? Make sure you didn't disturb anything inside the case, especially the heatsink/fan on the CPU or the plug for the fan. If you disturbed the heatsink, the CPU might be overheating, in which case the system will shutdown to protect itself. Also, many systems will shutdown immediately if no CPU cooling fan is detected, so be sure to double check the plug.

After you get that sorted out, try temporarily unplugging the hard drive (both the power & data cables) & then see if the system will boot & allow you to access the BIOS. You should also temporarily unplug ALL external devices except for the keyboard & monitor.

BTW, it appears your other post was deleted, probably because the moderator thought is was a double post.

message edited by riider


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#9
April 6, 2018 at 15:04:55
Not to be picky, but your answer in #2 indicates that something DOES happen. Running thru the POST screens is not nothing. I assume you had some video at that time?

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#10
April 9, 2018 at 05:43:25
Nothing showed up on the screen at all. I couldn't get into the BIOS at all.

I unplugged everything and left it overnight. I put everything back together and when I turned it back on, it started up, then it shut off for about 5 seconds, then it started up again and the 1, 2, 3 lights came on. Nothing was added to or taken away from the motherboard.


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#11
April 9, 2018 at 07:24:32
✔ Best Answer
If you see nothing on your screen, try swapping out the monitor and monitor cable from another computer to confirm that it is not just the monitor or cable that is bad.
Try any bootable CD/DVD like Live Linux, Seatools from Seagate (hard drive test), Memtest86 (memory test), etc. to see if it will boot from another source.
Try unplugging the hard drive as suggested earlier to see if it will boot to BIOS settings or at least show 'no boot drive' on screen.

You have to be a little bit crazy to keep you from going insane.


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#12
April 9, 2018 at 08:08:08
The monitor is fine. I connected it with a serial port connector and a DP connector.

I disconnected the hard drive and I did get a screen that said "Alert! Hard drive not found."

The 1, 2, 3 lights are still lit up.

I haven't done the Live Linux CD yet.


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#13
April 9, 2018 at 10:43:09
Right now the machine is up and running.

I re-installed the hard drive and after it did its POST test, it said "Boot drive not found." I restarted the machine and went into BIOS and reset the boot order. I restarted it and it went back to normal. I still don't know what caused the problem in the first place but at least I have some ideas on what to do if something like that happens again.


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#14
April 9, 2018 at 15:00:28
When the CMOS battery was changed you needed to enter the BIOS setup screens and reset values there. time and date, boot order are just two of the settings that may need adjustment.

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