Triple display support for Precision 7520

Hello LZLDMB,

The article posted here is for the older Precisions, however, still hold good. You are limited to 2 digital displays in this configuration, so the third has to be connected via VGA.

Hope this helps.

Thanks for the timely reply! Is there another configuration I could consider that has all displays digital?

Thanks Siba!

What are the limiting components of this configuration? I can replace the dock or add accessories to it. But if the limiting factor is in the graphics card or in the monitors, then I am stuck with 2D x 1A.

Thanks again!

It's the dock that is the limiting factor here. Is there a particular reason for going all digital? The VGA connection should support the monitors you have at their highest resolution.

The VGA configuration I have now is a bit blurry and off-color. I used to have DP running to it (before I added my third monitor) and it wasn't quite like this. So if there's a way to get back to digital, then I'd like to explore it. Thanks again for the help on this.

Before getting any other hardware you could try changing the VGA cable. If that doesn't help any, you may want to consider one of the newer models of docking station: the D6000, WD15 or TB16.

I was able to work with similar configuration.

*Laptop screen On.

*27" Dell Monitor on HDMI Port.

*27" Dell Monitor on Mini Display Port  (Using HDMI to Mini DP Adapter).

*Asus 15.6" Portable Monitor On USB A Port (Using USB-C to USB-A Adapter).

Every time I tried to do the Asus display thru the USB-C port, I would loose one of my 27" monitors. So above solution was my final working setup.

Hello,

I'm trying to project a different view onto each of my 3 different monitors and close the lid on my Precision 7520. Even though I'm connected to the 3 monitors (mini display port to hdmi, hdmi to hdmi, usbc to vga), the laptop can only project to 2 at a time. I've tested each monitor connection independently and they all work on their own, it's just that if all 3 monitors are connected, then the laptop will not project to one of them. Do you know how I can resolve this issue?

@bob_saget14  It’s possible that two of those outputs are driven from a common interface and therefore cannot be used simultaneously. The good news is that USB-C and Mini-DisplayPort both use DisplayPort for video output, and therefore both of those outputs are capable of running multiple independent displays from a single output. The device you need is called an MST hub. Here is one that works via USB-C, and here is one that works via Mini-DisplayPort. If you have to use HDMI on two of your displays and ancient analog VGA on the third because those are the only outputs you have available, then you might need an active DisplayPort to HDMI adapter/cable for one of the first two displays — not the more common passive type — and then a DisplayPort to VGA adapter for the third, all of which are active. MST hubs often cannot use passive DP to HDMI adapters/cables because their DP outputs often lack support for the optional “Dual Mode DisplayPort” capability that makes the use of those passive adapters possible. Or of course you could keep running one of the displays through a separate output rather than consolidating all three onto the MST hub.

Thank you for your thoughtful response. I've actually tried this type of setup before. I kept an hdmi to hmdi connection and then used this hub to connect the usbc output to the other 2 monitors. One monitor takes the vga output from the hub and the 3rd monitor takes an hdmi hub output. I've successfully used this hub to project 3 different views onto 3 different monitors using my personal laptop (Lenovo Thinkpad T470). However, there's a problem when I try this on my Dell Precision 7520. I can get the 3 different views on 3 different monitors, but one of the monitors connected to the hub will go black about every minute and then come back on a few seconds later. It's hard to work when one of your monitors goes out every 30 seconds so I've just been using 2 screens, but I would prefer to get the 3rd screen to work.

Is there something about the set up you suggested that makes you think the same screen going black every minute issue won't happen? I would hate to spend the $60 on that MST hub and continue to have the same issue.

The MST hub worked! Thanks a bunch for the suggestion. I admit I was skeptical but I gave it a shot and it works like a charm. This will make me better at my remote job so I very much appreciate it.

In case this helps anyone else down the road, here is the set up that allows me to project my Precision 7520 laptop to 3 different monitors.

• Laptop HDMI port to HDMI monitor port.
• USBC MST hub suggested by @jphughan
  • MST Display port to monitor Display port.
  • MST HDMI to monitor HDMI.

Thanks again!

@bob_saget14  Excellent news!  Glad I was able to help, and thanks for reporting back in case anyone else ever comes across this thread and benefits from the information!