Dell Optiplex 790 Issues

[River Valley Computer]

Brain scratching time.

We have a Dell Optiplex 790 i3 series on the bench. Had to replace the motherboard. No video. (yes we replaced RAM first).
Received replacement Fleabay motherboard last week - replaced it - same symptoms.
I didn't realize it but we had two other replacement MBs in the back storeroom that we had for spares way back when. Tried them - same exact symptoms. We also tried different CPUs also. Also tried 3 different power supplies.

Any ideas? We think it might be the case.

 

[seashore]

Is it the same when the motherboard is outside the case?
Is the monitor ok with other systems?

 

[nerd2u]

What video output are you using? Is the monitor detecting any source? Cable has been confirmed good?

Sent from my SM-G870W using Tapatalk

 

[River Valley Computer]

What video output are you using? Is the monitor detecting any source? Cable has been confirmed good?

Sent from my SM-G870W using Tapatalk

We have 3 monitors on that particular bench. Yep - we tried two diffefent ones.

 

[River Valley Computer]

Is it the same when the motherboard is outside the case?
Is the monitor ok with other systems?

Yes

Is it the same when the motherboard is outside the case?
Is the monitor ok with other systems?

Yes all 3 of them.

 

[Markverhyden]

Have you been able to force a POST beep code?

 

[River Valley Computer]

Have you been able to force a POST beep code?

Have you been able to force a POST beep code?

No we haven't but if the RAM is left out it beeps 1-3. Cmos battery new alos.

 

[mikeroq]

Let's try to get this straight.

First is this a No POST or No Video?
No POST = No video (maybe), booting halted, No OS loading.
No Video = Board posts, OS boots.

I'm going to assume it's a No POST since you didn't mention say hearing the hard drive being active, or the Windows startup sound through a possible internal speaker.

You have an Optiplex 790 and you replaced the motherboard and now it's not posting,.
You then ordered another motherboard and it doesn't post as well.
You tried to more motherboards you had on hand an they don't post.
You tried different processors and power supplies and no post.
You also tried different RAM and no post.
You tried bare board, cpu, ram, and PSU outside case and still no post.
You tried different video cables and monitors and still no post/video.

This leads me to believe there is a common component that has fubared these motherboards. I find it very hard to believe that 4 different motherboards all have the same issue.

Have you tried the original processor in a non 790 motherboard with a good power supply and ram?

I didn't see a mention to the diagnostic lights.
https://www.dell.com/support/articl...ex-diagnostic-indicators?lang=en#2009_to_2012

I would reinstall a board in the case and see what the lights show. If everything is good the lights should be off. They should go through a pattern until the OS boots. So if you hook it all back up and the lights cycle and then turn off maybe pop a video card in and see if you get video.

 

[River Valley Computer]

You summarized in perfectly! Yes we did try the original CPU in a 3010 - worked fine. We installed a Dell 1/2 video card (dvi) - no video. I think it is the work bench - it's haunted.

Seriously - three of us are so perplexed. We have read and read on the Internet. Just nothing in common. Ben does remember something 4-5 years ago about a problem similiar but he can't remember the details. We are a Dell Partner but they are NO help.

I really think the only real fix is three bottles of whiskey!

Thanks so much for all your suggestions everyone!!!!!!!!

 

[mikeroq]

You summarized in perfectly! Yes we did try the original CPU in a 3010 - worked fine. We installed a Dell 1/2 video card (dvi) - no video. I think it is the work bench - it's haunted.

Seriously - three of us are so perplexed. We have read and read on the Internet. Just nothing in common. Ben does remember something 4-5 years ago about a problem similiar but he can't remember the details. We are a Dell Partner but they are NO help.

I really think the only real fix is three bottles of whiskey!

Thanks so much for all your suggestions everyone!!!!!!!!

I am still curious about the diagnostic lights.

Sent from my Samsung Galaxy Note 9 while driv ik gndjfhd

 

[Larry Sabo]

Why not find a similarly configured Optiplex 790 that does post, then swap components one at a time until it no longer posts?

 

[NETWizz]

There are diagnostic lights in front... Check them.

https://www.dell.com/support/articl...e-dell-optiplex-diagnostic-indicators?lang=en

Also, consider checking the power button color. If it is amber, you may have a bad power supply.

 

[mikeroq]

Just like the link in my post above [emoji1787][emoji1787][emoji1787]

Sent from my Samsung Galaxy Note 9 while driv ik gndjfhd