Need help with DELL 2408WFP monitor. When turned on without graphic card connected, I get a a strange screen pattern at the bottom of three short vertical columns containing white bacground with several thin blue lines and another column on the right side top to bottom approx 3/4"wide of various verticle thin lines of varying colors, and the floating menu. When DVID1 is connected get the same pattern with distorted picture. This happens w/VGA.

To connect three monitors to a Dell Optiplex 7010, you can use the built-in DisplayPort (DP) ports and the VGA port. Here's how you can set it up:

1. Check the available video ports: As you mentioned, the Dell Optiplex 7010 has two DisplayPort (DP) ports and one VGA port. Make sure all three monitors support at least one of these connection types.
2. Connect the first monitor: Use a DisplayPort cable to connect the first monitor to one of the DP ports on the Optiplex 7010. Ensure that both ends of the cable are securely plugged in.
3. Connect the second monitor: Connect the second monitor to the other DisplayPort (DP) port on the Optiplex 7010, using another DisplayPort cable.
4. Connect the third monitor: Since the Optiplex 7010 has only two DP ports, you'll need to use the VGA port for the third monitor. Connect the third monitor to the VGA port using a VGA cable.
5. Configure display settings: Once all three monitors are connected, you'll need to configure the display settings to extend the desktop across all monitors. Right-click on the desktop and select "Display settings" (Windows) or "System Preferences" -> "Displays" (macOS). From there, you should be able to set the arrangement and orientation of the displays.

Note: When using multiple monitors, it's important to consider the graphics capabilities of your computer. The Optiplex 7010 might have limitations on the maximum resolution and refresh rate it can support across multiple displays. Check the specifications of your specific Optiplex 7010 model to ensure it can handle three monitors simultaneously.
If you encounter any issues or limitations, you may need to consider using additional hardware, such as a DisplayPort splitter or an external graphics card, to connect and support three monitors.

cause, unknown. Usually the fact that they come and go, indicates a short. that means defect. Call the mfr and get it replaced if it is warranted.

> one long and three short BEEP

Something is wrong with some of your hardware.

Turn the computer off.
Disconnect the AC power.
Remove the graphic card.
Connect the AC power.
Turn the computer on, to see if the pattern of BEEP has changed.

Turn the computer off.
Disconnect the AC power.
Remove the RAM -- all of it.
Connect the AC power.
Turn the computer on, to see if the pattern of BEEP has changed.

Turn the computer off.
Disconnect the AC power.
Reinsert one stick of RAM.
Connect the AC power.
Turn the computer on, to see if the pattern of BEEP has changed.

Turn the computer off.
Disconnect the AC power.
Reinsert the graphic card.
Connect the AC power.
Turn the computer on, to see if the pattern of BEEP has changed.

Well it seems to me you have a dead pixel issue. As soon as you call up a company like Dell and tell them that they know they have to replace the unit.

Either ride it out, or replace the actual LCD part of the screen. Which can not only be costly but rather complicated as well... If you want to go down this avenue then take apart the back of the unit carefully and remove the whole screen unit inside the plastic housing. The screen unit should consist of 3 glass thin slabs and a plastic type screen over the front wrapped together by a sticky reflective tin-foil type substance. Thats the unit you need to replace... Make sure you remove the back-light lamps from the top and bottom of the unit carefully, as if you break these your heading down a whole new avenue of issue...

On the back of that device will be a part number...

www.sparepartswarehouse.com

go there, type in the product number and it will search their database for a replacement part...

Another option is to search ebay until you find an AS-IS deal on the same make/model with an instact screen... Which requires patients and your always taking a risk doing this...

It might be the monitor is faulty or you do not have your latest drivers on your graphic card or the card is overheating.

Hit menu button on the screen located three buttons left of the power button. Select Auto Adjust. The display will automatically adjust the screen to the centre. If your display is like mine, you may have to repeat these steps several, several times to correct the problem.

This looks like a sign that the monior is failing. Your best bet is to contact Dell and ask for advice.

If it is a Dell Ultrasharp 2408WFP it can display a max of 1920x1200.

Mirage 3 is integrated graphics I believe and integrated graphics have no business running such HD resolutions such as 1920x1200. It will choke or refuse to do that resolution generally.

Other 24" Monitors can do a max of (1920x1080) which is basically 1080 HD resolution. You need to find which monitor you have, what its max resolution is, and then find what the max resolution is that your SiS Mirage 3 can output.

Is the card plugged into the (PCI/AGP) slot correctly? Did you disable the onboard video in the bios? Also be sure to check in windows device manager and check for the graphics card to appear there.

I have similar problem.  I'm using the HDMI connection from my PC to the monitor and when I connect my audio out from the monitor I get hissing and popping sounds along with the audio.  It sounds pathetic, I also hear the music and audio along with the hissing and popping.  
If I connect the audio to the back of the PC the sound is crystal Clear.  I am using Vista 64 bit with NVIDIA GeForce 8600 GT video card.  Trying  to Google to see if others are are seeing the same problem.  I just got my monitor on Oct 6.