I have a E7240, a (brand new 32 inch) 4k monitor and an E-Port Plus. Several of these setups actually, I am a huge fan of the E series laptops. When I plug in the new monitor into the side of the integrated mini display port on the laptop, it works fine, I get the full 4k at 60hz. When I connect the laptop into the dock, it automatically routes the video signal through the ports on the back of the dock.
Note that this is an older E series dock, not the E-Port II with USB 3. So the display ports on the dock are not "DP 1.2". Everything else about this dock is great, the gigabit ethernet, audio, power, USB, etc. These are all I need -- I don't want to purchase the newer dock for over $200 more dollars. My preference would be to just drop the laptop into the dock, and plug the monitor cable into the side integrated mini display port, directly on the laptop. Yes, its 2 connections each time, but its just a few seconds to do it.
I figured that I could go into device manager (Win 8.1, 64 bit) and disable the video on the "dock", but it doesnt appear that simple. I've been reading up on some forums and Dell claims that it is a "pass through", hence the name port replicator over dock. Unfortunately, the reality is that it is a pass though with a downgrade of the video signal.
Any ideas on how to "route" my video signal directly out the (natural / integrated) side of the laptop, rather than through the dock would be appreciated. I've got several of these setups and at 200 a pop, that is a lot more money to add to my already expensive 4k monitor upgrade(s).