As mentioned in the title I have both pieces of hardware. I also just purchased a third Dell U2414H LCD monitor. I am trying to connect all 3 via display port. However it seems that all I can do is 2 monitors? When I try to daisychain them I got 2 monitors mirroring each other and one through HDMI off the laptop.
Is this a physical limitation of the replicator? Is there a firmware update somewhere?
The E6520 comes with Intel HD Graphics 3000. The specs for that GPU are buried in the specs for the CPU itself, but if you go to ark.intel.com and look up your CPU, then scroll down to the graphics section and verify that it shows Intel HD Graphics 3000, you'll find that that GPU only supports 2 independent displays, which is why you see mirroring. More recent Intel GPUs do indeed support 3 displays, but no Intel GPUs to my knowledge yet support 4.
If your E6520 has the NVIDIA discrete GPU, I can't find any information on NVIDIA's site about maximum number of supported displays, but based on your experience I would assume it's 2 unless indicated otherwise.
The E-Port docks that include a pair of USB 3.0 ports in the back (they're blue) also support DisplayPort 1.2, including MST -- assuming your system, GPU, and drivers all support MST as well, of course, and I don't know if your system does. The original E-Port docks that only include USB 2.0 ports do not seem to, since MST support was billed as a new feature for the updated E-Port dock.
So then I SHOULD be able to use MST out of 1 of the ports, right? and use a single monitor on the other port. Correct? Or am I still being limited by the video card....?
If your dock has USB 3.0 ports, it won't create an OBSTACLE in terms of using MST -- but as I said above, your system, GPU, and drivers all need to support it in the first place; the dock being MST-capable doesn't substitute for the requirements on those components. I just don't remember whether that system and the Intel HD Graphics 3000 GPU support MST.
Well again, I'm not sure about MST either way on that GPU, but you should be able to find that out. However, while looking for something else I did stumble on this Intel FAQ page dedicated to triple display configurations. The GPU list linked in one of the FAQ items indicates that triple display support arrived with the Intel HD Graphics 4000. That GPU also definitely supports MST since I have a system with that GPU where I've used it, but again I just don't know about the 3000. Link: www.intel.com/.../graphics-drivers.html