RE: M4800 and Optimus?
Dell's article "Why the Precision Mobile Workstation M4800 systems may not have a Switchable Graphics BIOS option"  is demonstrably mistaken on at least one claim according to their own Owner's manual service instructions, the Intel 4th Generation Mobile core datasheet, and the Optimus technical white paper.
The article's 2nd claim is that the QHD+ screen utilizes an Embedded Display Port (eDP) connection that is unsupported by Intel 4th generation Core Mobile processors. Intel's datasheet, Table 1, Sections 2.4 through 2.7 detail unmistakably the Integrated graphics platform support for eDP and it's support for "muxless switchable graphics".
nVidia's own Optimus technical whitepaper describes how the dedicated GPU (dGPU) requires the Integrated Graphics Processor's display controller to accept the output from the dGPU for output on the screen.
From this, it is readily evident that both GPU's are on the path to a display controller which then drives multiple outputs. In fact that seems to be how the m3800, xps15, and the m4800 non-QHD systems all work.
Secondly, the article reflects significant confusion surrounding the use of the terms analog and digital. LVDS is a digital signaling standard. Flat Panel Display Link (FPD-Link) is long-standing implementation of LVDS for video data transfer. You've probably seen LVDS used elsewhere in SCSI, FireWire, and other technologies.
I don't know what the m4800 design does, that the other equipment doesn't. I think I can prove this self-published by Support Professionals explanation flat out wrong.
Now, maybe they completely shut down the HD 4600 and then connected the display output only to the Quadro Kx100 chips. I can't tell. I haven't found nVidia's datasheets yet. If the silicon is at all connected passing through the IGP display controller, maybe there's hope.
I'd love to see a comparison of Original Device Manufacturer screen model #'s so we could compare them across Dell product lines to see any differences. Perhaps over in the m4800 owner's thread.
If there's no hope, the new Toshiba Tecra W50 offers an interesting alternative to the W540. FHD only I think. For Dell, I have to decide if I'll be allright with the FHD. I like AMD, and I'll get Enduro. If Dell didn't get the flagship video right, what else did they get wrong is my big concern.
If nothing else, I hope this article prods engineering into an actual clear cut explanation or a better investigation. Smarten up Dell, while you still have the chance to earn our money.