Thanks. When I search about this I get many stories like yours about having to use hacks and tricks to get things working. I am hoping this is just for laptops not on Apples list.
Is the current rMBP 15" plug and play for 4K scaled to 1440p @ 60hz without hacks?
ps
Quite amazing you can drive 2 4K displays at 60hz with 1440p scaling on a laptop with integrated graphics. How is the performance with 1 vs 2? Any stuttering?
Two bits, although I'm still happy with my displays!
First, the use of the word "hack" is a end-around to get unsupported-by-Apple and/or unsupported-by-vendor 3-party (non-Apple) displays "optimized" for a particular system-display combo - the EDID hack is only one of several means to create a file that allows a Mac, Linux, or Windows PC to communicate with a display that is not fully supported on an OS platform. The "hack" that I used created a display override directory file - which includes the SN and other data specific to my display. These hacks have been used for years, and I first used them on Windows PCs several years ago - IMHO because display manufacturers DO NOT write drivers and other display-specific software for their displays and/or for all platforms.
And, yes, it's saddening to have to resort to get some really cool toys on our desks and laps.
These overrides help - in some instances, but not in all instances - a PC communicate with a display to "find out" what that that display is capable of. The override process helped my rMBP immensely, but didn't do a thing for my 2012 Mini Server; my rMBP is connected by mDP>DP to both displays and my Mini is connected by mDP>mDP to one of the two displays, and I actually get more pixels and better display appearance on my Mini without an override in place.
Also, I view SwitchResX as an "override" utility for displays, and IMHO with the advances of 10.10.3 this utility is not necessarily needed anymore to get the most out of my Dells, but it's now become a very convenient utility to layout my workspaces - my two Dells are on arms and I move them around to suit my workflow, and SwitchResX provides the ability to create and save workspaces. Nifty, that. If you view SwitchResX (and other utilities like it) as a means to better "drive" and/or customize a display, because (in my case) Dell didn't - it's easier to get one's head around than by calling it a hack.
Keep in mind that Apple has included several overrides with the stock OS install (System>Library>Displays>Overrides) - most display models have it's own special set of capabilities, and it's up to Apple and display makers to provide more/better sets of overrides, or, in my words "instruction sets".
And, to clarify, my rMBP has the discrete Nvidia 750M GPU - which drives all 3 displays (both Dells and the internal display), all at up to maximum resolution, and all at up to 60Hz. Given the power of the newer integrated GPUs and that all of the 15" rMBPs have both TB2 and 16GB of RAM, I see no reason for the newer laptops to be as capable as mine; there is at least one poster in the P2715Q thread that was driving a widescreen LG TB display and a
daisychained P2715Q at full resolution and at 60Hz - and that was before 10.10.3 came out...
I still have a bit of experimenting to do with my layout, but I have to wait until an order from Amazon comes in next week...