How to: multiple monitor setup for Dell Optiplex 790

I currently am recommending the Dell Optiplex 790 minitower. (This will work for the desktop configuration as well.) It took me a lot of time and multiple returns to figure out the best way to do dual monitor, triple monitor and quadruple monitor setups (two monitors, three  monitors and four monitors). Here is what I found works the best:

Dual monitors: The simplest and cleanest way to do it is to buy a DisplayPort to DVI (male to male) 6 foot or 10 foot cable. The 790 has the capability of using the DisplayPort jack in the back as a second monitor without buying another video card. Here is an example of the cable. Note: this will only work for you if one of your two monitors has a DVI (white) jack. I have also used a DisplayPort to VGA adapter successfully over the last month (this is the exact adapter). You are able to choose either a cloned view or independent screens using either Windows’s Display settings or Intel Graphics settings (click here for Intel’s instructions).

Triple/quad monitors: I found that I couldn’t use my trusty Radeon 7000 PCI cards in Windows 7 machines, so I chose to go with the ASUS Radeon HD 5450 PCI-Express (here is the Amazon link).  I chose this video card because it is reasonably priced (with no need for gaming) and that there is no fan to reduce the chance of failures. In the 790, you can actually buy two of these PCI Express video cards and put them both in! (See this PDF for motherboard card slot info.) I’ve done it and it truly works with three monitors and I’m sure it would for four.

Please comment with your own experiments and successes on the 790 or similar models.

26 replies
  1. Nelson
    Nelson says:

    Woohoo! Bought the same video card (already had an ATI Radeon 5450) and I was finally able to get my 3rd display. Only issue now is that there is some flickering or line noise which is bothering me (could be driver issue). But I’ve got my 3 monitors now and it looks awesome and I’ve got so much more real estate now to work with. THANK YOU for this post. Had you not posted this I would still be fumbling in the dark. Appreciate it a lot!

  2. Paul
    Paul says:

    In your 2 monitor setup, are the screen 2 copies of the same thing, or are they two independent screens that you can extend the desktop on? Thanks.

  3. brmorris
    brmorris says:

    You can choose either, although with a clone, it is best to have monitors that have the same amount of pixels.

  4. geof
    geof says:

    my dell optiplex 380n is failing to run two cards. I added a vga express card and it disabled the integrated card. Any ideas?

  5. Nohra
    Nohra says:

    Has anyone else tried with the cable?
    I have the same question as Paul. Do you get the same view on both? Thanks!

  6. Fred
    Fred says:

    Can you use a PCI Express video card and the displayport to DVI adapter cable to support three monitors or do you have to have two PCI express video cards? Most video cards indicate that two of them won’t work due to the small power supply in the 790 not providing enough power.

  7. brmorris
    brmorris says:

    Fred,

    I’m pretty sure that one PCI Express card disabled the integrated graphics totally, so the VGA nor DisplayPort work. I added the two PCIe cards in two 790s early in 2012 with no problem so far. A better video card that requires more wattage would obviously be more of an issue.

  8. Ty Brown
    Ty Brown says:

    I installed a nvidia 265 card on a 790 in the x16 pci slot works fine

    I moved it to the x4 it works fine however when install 2 cards on the x16 slot works but it shows up in the bios. Any thoughts.

    I’m using the same time of card in both slots. And they both work.

  9. Ty Brown
    Ty Brown says:

    Its been resolved. Still dont know what happened. There are 2 pci-e slots on a dell optiplex 790 one is 4x and the other is 16x for some reason i couldn’t get video cards to work in both slots at the same time. They would be seen in the bios. But not in windows 7 x64 i called del support and when i tried it for him it worked… go figure

  10. brmorris
    brmorris says:

    What is your purpose? A second monitor or to use the VGA jack in the computer to a DVI in the monitor? I don’t think this is what you need..

  11. john
    john says:

    In my 790 I am running Win8x64 and have a dual dvi card installed. I can run 2 monitors off of the one card. I have tried hooking up a third monitor with a display port to dvi adapter. When I do that, non of the monitors will display. I can either leave the 2 port board connected and have 2 monitors, or the display port and get 1 monitor, but never 3.

    I tried working w/Dell support – and the impression I got is that I’d need to wait for a bios update to correctly support > 2 monitors in Win8. I’m running the latest bios, and there has been no updates since then.

    If I can’t get this to work with the card I have now – I may try to do a setup identical to yours to see if I can get it working. Any ideas?

  12. KYoshi
    KYoshi says:

    We’re running on OptiPlex 790 sff and tried setting up a dual monitor setup via your initial write-up: (No. 1 Monitor) VGA and (No. 2 Monitor) VGA to DisplayPort. Both monitors are running, but we are only getting cloned desktop on both.

    Current OS is Windows 7 Pro and in the Control Panel > Hardware and Sound > Display > Change Display Settings, there is no option to change the display mode from Clone to Extended Desktop. Hitting Detect has no effect.

    Does the extended desktop function require an additional video card to be installed?

  13. brmorris
    brmorris says:

    KYoshi,

    No, I’ve set this up dozens of times now and typically setup extended desktop. Try opening the Intel display setting app instead to configure the video.

  14. Tim
    Tim says:

    I use a 790 at work w/Win 8-64, an i5 2nd Gen & 8G of RAM. It has a nVidia GeForce 8400GS VC, and onboard VGA & Display Port. (The machine has the latest BIOS version and chipset drivers too, along with the current NVidia software.) I am running 2 monitors from the nVidia card and would like to run 2 more monitors on this machine (as there is a second PCI express VC slot. I have seen this done by a former tech that I worked with who has left (I can’t seem to get up with him for the solution so I am here). Is there anyone out there that can shed some light on this. It would be greatly appreciated and would make work run smoother too. Thanks in advance.

  15. chuck
    chuck says:

    I had a similar problem awhile back, trying to run a ppt show on two monitors–one of which was remote and connected via ethernet (hdmi/ip). “Extending” the displays worked, but not “duplicating” them. No success until I discovered that the two monitors must be set to the same resolution.

  16. brmorris
    brmorris says:

    Right, and Windows 7 generally will handle dropping both monitors to a highest common denominator resolution.

  17. Tiffany
    Tiffany says:

    Will the Asus HD6450 provide the same results? I contacted Dell and they recommended that one and the ATI Radon HD4550.

  18. brmorris
    brmorris says:

    Tiffany,

    I think either would work ok — I like that they both have no fan to fail. The only thing I’m not sure of is what the limits are of the second PCI Express slot and what types of video cards will and won’t work in it.

  19. Worker123
    Worker123 says:

    Can I use a VGA connector with no issues. I want to clone the display using the DP using a DP to HDMI but nothing appears on the screen I have checked the setting in display but only the VGA monitor shows up. I have tried pressing the identify button but still only the VGA connected monitor? I have tried pressing the windows logo +P like on a laptop but nothing happens? The second screens HDMI slot works fine with everything else please help

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