OptiPlex 790 Desktop - No Video on Startup

If you remove all cards from slots and remove all cables except for vga attached to the onboard video you should be able to turn on and see an error.

These models will not show video onboard when a card is in the slots.

That is not a supported video configuration.

There is no secure boot for bios on any 390 790 990.  These systems support MSDOS and XP and therefore will NEVER have windows 8.x / 10  secure boot UEFI.

Well, that's only part of the problem.

I can't see the BIOS or any of it's errors, so I don't really know what's going on. There are some error lights but they seem to be generic errors. (The status lights are 1, 3, and 4 with a solid blue light, which just seems to be generic. I can change that to 1, 2, and 3 when I take out the SSD. I concluded that the problem was with the SSD, but maybe that's wrong.)

I'd like to get it to display something so I at least know what I'm doing.

Then disconnect the SATA Data cables from any drives and remove ALL RAM.

Turn on it should beep.

Then put 1 ram stick in at a time and test.

390 790 990 does not have a "splash screen"

https://www.youtube.com/watch?v=udGOe7LQJEI

When a card is in the slots the screen will say.

System halted!
Attention: Unsupported Video Configuration Detected

Action is Required

This computer has an add-in graphics card, but the monitor is plugged
into the integrated video connector.
To attach the monitor cable to the add-in graphics card:

1. Shut down the computer
2. Plug the monitor cable into the add-in graphics card connector.
This may require a video adapter or video adapter cable.
(provided with the system)
3. Turn on the computer.

This message should not appear after completing these steps.
For more information or help, please refer to the system documentation

There is no video card, or for that matter, any cards at all.

I tried this, but the result is the same. If I try to go into the boot menu it doesn't show on the monitor.

The boot menu is from the bios. Nothing whatsoever to do with any os on a hard drive.

Thats why you disconnect everything.

You remove all ram.

You put 1 stick back.

It should post with an error displayed.

Solid amber power button means dead cpu or motherboard.

I have done this, again. It's just a solid blue light with one, two, and three. (When the system has one memory stick and no SATA plugged in.) There is no error code that is displayed other than the diagnostic lights.

The problem that I am trying to fix is that there is no output on the display.

The SSD was an additional issue, not the one I am currently trying to fix. I am trying to fix this issue first so I can worry about the SSD later. Sorry if I did not make this clear earlier.

I have already tried this, and it does not solve the problem.

I *just* want to get video working so I can see what it is try to display. That will help me further see the problem.

Sorry if this was not clear.

Also, I bought my 790 DT as a refurb.  The first thing I had to do to it was replace the size 2032 CMOS battery.  A low or dead battery can cause all sorts of bizarre problems.

Duracell or Energizer is suggested.  Sony lithium only lasted me 2 yrs. when they should last around 5.

Hi @cdde,

I'm surprised nobody asked what monitor and model # you are using.  Your display scenario I've seen before here in Dell Community.  The monitor was too new for the PC, so no image until OS kicked in with the appropriate graphics driver.  I don't recall seeing a fix for it at the time or if the monitor was a Dell.

"390 790 990 does not have a "splash screen"" - The 790 does to have a splash screen.  I also have a 790 DT.

The 1,3,4 diagnostic lights with blue power light can definitely be a concern.  I pasted from Dell's diagnostics at the bottom of this post.

Dell Diagnostic Indicators 

Optiplex 790 Tech Guide 

I may not have a direct answer for your splash screen and BIOS not displaying, but hopefully helped in some way.  If you reply with your monitor and its model #, another Rockstar or expert should hopefully be able to assist.

@bradthetechnut 

Top Rockstars usually specify only DL 2032 batteries. These are very special, You can only buy them at certain drug store chains.

Many computers use standard cr2032 batteries. Plain 3V lithium cells. But they won't work in our dells, which require the DL (duracell brand) part number.

Try it ... machine won't boot with any other brand battery!

Hi @donm4599x,

This time, I can't exactly tell if you're serious or not, and am hoping not.  I have Energizer in mine.

When the Sony battery went low after 2 yrs., my PC still booted and worked fine; except it wouldn't finish downloads.

@donm4599x,

Do you think a GPU card would solve @cdde's problem?  Probably harder to tell until we know what monitor.  If the monitor is too new for the onboard graphics...

Anything is possible Brad, but I doubt if a gpu card would help. In his OP, he says he is using vga cable, so the monitor must be capable of it. It sounds like he tried more than one cable and monitor too.

If a new video card indeed worked and the onboard video is just bad, I still wouldn't trust the system. Because video circuitry is on the cpu chip, so if any part of that chip is flakey, I wouldn't trust any of it.