Multiple monitors issue on Dell Latitude E5470

No Intel GPUs currently on the market support more than 3 independent displays.  The only way to use at least one of the external displays through a dock or adapter that used DisplayLink "indirect display" technology (not to be confused with DisplayPort).  You could plug a DisplayLink USB adapter into the USB 3.0 port on your existing dock, for example, and connect one of your displays to that.  However, DisplayLink can introduce a number of drawbacks over connecting displays to a native GPU output.  It will probably be fine if you just use these displays for basic productivity tasks, but for technical reasons I can summarize if you're truly interested, DisplayLink will NOT work well in use cases that involve large areas of the display changing simultaneously, such as full screen video or gaming.  You might also see compression artifacts and/or juddery motion if your USB bus is heavily utilized, such as when transferring files to a USB external hard drive, or especially an SSD that can use more bandwidth.

One minor additional note  If any of your current displays supports DisplayPort daisy-chaining by including a DisplayPort output, and at least one of the other displays has a DisplayPort input, you should consider daisy-chaining them.  That would allow you to drive two displays off your dock's DisplayPort output and the other one off DVI.  The reason I suggest this is simply that VGA is obsolete and looks noticeably worse than any other connection option because it's the only connector that still uses an analog signal for video rather than digital.  Note that in order to do this, you'll need the E-Dock II that includes USB 3.0 ports (blue ones on the back) because that generation added support for DisplayPort MST.  The original E-Dock that only has USB 2.0 ports (all black) does not support this.  Or if you the DisplayLink-based solution above, if the display you're currently using over VGA also has a DVI or HDMI input, get a USB to HDMI adapter rather than a USB to VGA adapter, and then use either an HDMI cable or an HDMI to DVI cable/adapter to connect that display.  But whatever you do, try to get off of VGA.

@jphughan Related to this issue:
q3: how does e5470 assign 6820hq 16 pci-e lanes to different interface/ports? 
q4: how many lanes does MST hub take up these pci-e lanes? or it does  not take cpu pci-e lanes but directly treated as one independent and simultaneous display to hd530?  if so hd530 should be able to support 2 external MST hub along with e5470 hdmi, does dell have a dock supporting 2 simultaneous mst hub for 2 external dp1.2 4k@60?

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@wtnwin111 wrote:

@jphughanRelated to this issue:
q3: how does e5470 assign 6820hq 16 pci-e lanes to different interface/ports? 
q4: how many lanes does MST hub take up these pci-e lanes? or it does  not take cpu pci-e lanes but directly treated as one independent and simultaneous display to hd530?  if so hd530 should be able to support 2 external MST hub along with e5470 hdmi, does dell have a dock supporting 2 simultaneous mst hub for 2 external dp1.2 4k@60?

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I’m not sure why we’re talking about PCIe lanes here because they have nothing to do with DisplayPort, but....

1) I’m not familiar with the PCIe architecture of the E5470 specifically, but there are PCIe switches, so the CPU could have an x16 interface to the switch and then the switch has an x16 interface to various other components, allowing each device to consume up to x16 bandwidth (if nothing else is active), but only a max x16 total bandwidth back to the CPU for all devices attached through that switch. Ethernet works this way, for example.

2) MST hubs do not use PCIe. They take a DisplayPort 1.2 signal (which is not carried over PCIe even within the system) and can split it into separate signals for separate displays. But a 4K 60 Hz display requires almost the entire bandwidth of a DisplayPort 1.2 source signal, so if you wanted to run that kind of display, there would be no point having an MST hub involved. The E-Port Plus II (second generation) dock with USB 3.0 ports also added DisplayPort 1.2, and it has two DisplayPort outputs, but using two full-bandwidth DisplayPort 1.2 connections simultaneously still requires that the system actually provide two full bandwidth DisplayPort 1.2 signals out of its dock connector, and according to the KB article linked below, only systems with discrete GPUs are set up that way. Systems that have Intel GPUs only send a single DisplayPort 1.2 channel to the dock, which can then be split up via MST to multiple displays, but the total bandwidth requirements of the multi-display setup still has to remain within the capacity of a single DP 1.2 channel, which isn't enough for dual 4K 60 Hz. Link: https://www.dell.com/support/article/us/en/19/sln300546/e-port-plus-and-4k-displays?lang=en

@jphughan thx, then if I bought E-Port Plus II (second generation) dock, once it connects my e5470, are both e5470 built in hdmi and dock dp ports work simultaneously?  If it can, it seems I can connect a 4k@60 to dock dp port and a qhd 2560*1440 @60 to built-int hdmi port to set up 3 monitor working simultaneously?

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@wtnwin111 wrote:

@jphughan thx, then if I bought E-Port Plus II (second generation) dock, once it connects my e5470, are both e5470 built in hdmi and dock dp ports work simultaneously?  If it can, it seems I can connect a 4k@60 to dock dp port and a qhd 2560*1440 @60 to built-int hdmi port to set up 3 monitor working simultaneously?

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I believe that setup will work, but I haven’t tested it.

I realize this is an older post but I'm having such a problem I just got to ask a quick question. I just read something about DisplayPort technology and I'm wondering if that's my sole issue. I don't have a DisplayPort adapter so I'm just out using it.  But I have bought every other adapter and have thus far been limited to one additional monitor beyond my laptop screen.  I've used VGA DVI and HDMI all without any result. Whether with or without the docking station.  

I would just like to make some forward progress at this point. Thank you.

@tfrasierthe more detail you can provide about your setup, the more likely you'll be able to get useful replies.  Please indicate the specific displays you're using, or at least the resolution(s) of the displays and the inputs they have available, as well as what sorts of cables you've tried and in which direction.  That matters because for example a DisplayPort to HDMI cable only works for connecting a DisplayPort output to an HDMI input, not the other way around.  Please also specify which CPU your specific system has, since that might affect which Intel GPU your system has.  I believe all CPUs in the E6430 have an Intel GPU that supports 3 simultaneous displays, but I'm not certain about that.  But if so, then as long as you have the required connectors available, you should be able to run dual external displays.  I've seen a few threads where people have reported that certain built-in display outputs of certain system models can't be used simultaneously, but unfortunately I don't remember what system models were under discussion in that thread, never mind which display outputs.  But if you have an E-Port docking station available, you should absolutely be able to run dual external displays.  With the regular E-Port docking station, one of the two displays would have to be connected over VGA.  With the E-Port Plus docking station, you can connect both via DVI or DisplayPort.

Lastly, if you choose to disable the built-in display, can you currently use both external displays?  It would be useful to know whether the specific limitation you're currently running into is either a) the inability to run 3 displays total, or b) the inability to run two external displays, even if they're the only two that would be active.

Thank you for responding. I would get the same result as just plugging a VGA into the side port.  I have a pro 3x docking station, an Imagequest l705 VGA, Dell 1703FP DVI.These are plugged into the respective ports on the back of the docking station.  It will see all three screens but always tells me that whatever display #2or #3 is, isn't active. 

I can achieve the same thing without the docking station when I plug in a DVI monitor to the HDMI connector port with a Dell VGA monitor plug into that port.

I'd say I've been working on this for 3 months.

@tfrasier  at the very least you should be able to use both external displays simultaneously if you FIRST set the internal display to "Do not use this display" in Windows Display Settings.  Apply that change so that the only active display is one of your external displays, then try to setting the second, inactive external display to Extend mode and apply that change.  Does that work?  If so, then it's possible that your CPU has an Intel GPU that only supports 2 simultaneous independent displays.  You didn't mention which CPU your system has, so I can't verify that myself, but you can do so by going to ark.intel.com and drilling down through the selector to your specific CPU.  The GPU specs will be listed in there.

If you can't get two external displays running even after setting your built-in display to "Do not use this display", then I'm not sure what to tell you because that system can absolutely use dual external displays.  I had an even older E6420 in the past and did that on a regular basis, although I don't recall ever trying dual external displays plus my built-in display.  I personally can't stand trying to use the built-in display and external displays simultaneously.

I suspect I am cursed. I clicked on monitor one which would be the laptop itself but it doesn't give me the option to not use that display which oddly enough is always an option with the other ones.There was an option for having a duplicate on displays 2 and 3 but when I clicked on that that wouldn't work either.

How am I supposed to tell which CPU my computer has?

@tfrasier  make sure the external display is set as the primary display first, i.e. your desktop icons and Start button show up over there.  After applying that change you should be able to turn off the built-in display.  If you're still having trouble, make sure you have the latest Intel Graphics drivers installed.

@tfrasier  there are many ways, most of which could be revealed by Google, but if you're on Windows 10, one easy way is to right-click your Start menu, click System, and look at the "Processor" field in the "Device specifications" section.  If you're on an older version of Windows, opening Device Manager and expanding the Processors section will show one or more processors of the same name.  There will be one for each core (or logical processor on CPUs that have Hyper-Threading), but they'll all be the same model.

i5-3320 . Windows Pro 1903  8/13/2019 build 18362.418