Latitute 7490 w/ WD15 docking station: Setting up 4 monitor

Question

When I setup four monitors(HDMI, DP to mini DP, VGA and Diamond display link USB adapter) with WD15 dock to a Latitude 7490, one of the displays(VGA) with resolution 640x480 and I'm unable to change it as its grayed out. I know for a fact that WD15 wont support more than two display in HD with few Latitude models due to DP 1.2 USB-C limitation. Does this apply to Latitude 7490 as well? If yes what is the work around apart from connecting a display directly to the Laptop.

jphughan · Accepted Answer

Yes this limitation also applies to the Latitude 7490, and even the newer Latitude 7400. In fact it applies to almost every system on the market today because almost all laptops have that output wired to the Intel GPU even if the laptop also has a discrete GPU installed, and except for the brand new 'Ice Lake' Intel 10th Gen CPUs that include a new Gen 11 GPU and that launched literally a few weeks ago, all Intel GPUs on the market are limited to DisplayPort 1.2 over USB-C. In fact, even some of the new 10th Gen Core models still have this limitation because not all variations of that CPU generation include that new Gen 11 GPU; only the ones with 'G' in their model name do. So for example the 10th Gen CPU in the new XPS 13 2-in-1 has the new GPU, but not the 10th Gen CPU in the new XPS 13 'regular' model.In addition to that limitation, all Intel GPUs, including the new Gen 11 GPU, are limited to 3 independent simultaneous GPU-driven displays anyway, so that would be a problem too. However, 'indirect' displays connected via USB adapters or docks that use DisplayLink or similar technology do not count toward that limit since they’re not driven by the GPU. So in terms of a workaround, you’d need to connect two displays via that type of Diamond USB adapter. Those can both be connected to the WD15 by the way, since the display data they’re receiving is counted as USB data, so it won’t 'count' toward the max display limit on the WD15 itself, nor toward the GPU’s limit.Or if your 7490 was ordered with Thunderbolt 3, which is optional on that model, you could use a dock like the TB16 or WD19TB to potentially run 3 displays directly from the GPU. I say 'potentially' because you didn’t specify the resolution(s) of your displays. This might be an appealing option if some of the drawbacks of indirect display technology would negatively affect your use case. I wrote a detailed post about that in this thread, specifically the post marked as the answer. The question was about gaming but my answer applied more broadly than that: https://www.dell.com/community/Alienware/Docking-Station-D6000-Very-Bad-Video-performance-for-gaming/td-p/6193369

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