I have a Latitute E5580 w/ WD15 docking station but I haven't get it to work with three external monitors. From the dock station I use the three video output (VGA, HDMI 7 Mini DisplayPort) but I just get 2 monitors with the recommended resolution (1920x1080) and the 3rd one with 640x480 or 1280x1024 which it looks blurry and flickers (I've tried with different monitors)
Could you help me out?
The WD15's product page, FAQ page, and manual available on support.dell.com all specify that the WD15 can handle up to two 1080p displays or a single 2560x1600 display. When you already have dual 1080p displays connected, there simply isn't enough bandwidth to run a third display at a useful resolution. This is a limitation of USB-C when used with a docking station and on a system that only supports DisplayPort 1.2 via USB-C, which is most systems at this point because Intel GPUs don't support the newer DisplayPort revisions over USB-C yet. I wrote a detailed post about USB-C's operating modes here if you want more info about that.
If you want 3 displays, then if your 5580 was ordered with the Thunderbolt 3 option, your best option would be the TB16 dock instead, which can tap into 4x more video bandwidth than the WD15 because it uses Thunderbolt 3 rather than USB-C. (Note: It's just a Latitude 5580, not an E5580. The "E" was dropped from Latitude models that don't have the E-Dock connector on the underside of their chassis and instead use USB-C/TB3.)
If your 5580 doesn't have the Thunderbolt 3 option, the only other options would be:
- Connecting one of your displays directly to your system so that its bandwidth requirements don't have to be met via USB-C.
- Using a DisplayLink adapter for the third display, such as USB-A to HDMI/DisplayPort adapter, which you could plug into one of the WD15's USB ports because DisplayLink sends video as USB data traffic. However, DisplayLink has some significant downsides compared to displays that actually tap into native GPU outputs.
- Use a dock like the Dell D6000, which uses DisplayLink at the dock level. This is a bit cleaner than a WD15 plus a DisplayLink adapter for just the third display, but now ALL of your displays will be driven by DisplayLink, which again has its drawbacks. Additionally, the D6000 only provides 60W of power to attached systems, which may not be enough to power the Latitude 5580 properly.