SO the new Haswell rMBP's explicity state 4K output from their HDMI 1.4 ports....do you think Apple will enable this for our mere mortal Ivy Bridge rMBP's? Would seam like a mean thing to not given the hardware is more than capable...plenty happy with work arounds or 3rd party stuff but native support is always great. Grr only thing I'm mad about is lack of thunderbolt 2 on my Ivy Bridge rMBP...still erks me that they didn't just have Thunderbolt support 20Gbps from the get go especially since Thunderbolt 2 doesnt really add bandwidth rather it couples both 10gbps lanes into one big 20gbps lane. Oh well at least I have two ports. Now to try 8K output! Kidding...
Yes, Apple enabled this on Ivy Bridge in Mavericks. I can now use my 4K TV at 30 Hz without my patch on my 2012 15" rMBP. However, HiDPI support does not work anymore - it seems that Apple removed HiDPI support for external monitors from Mavericks. I am no longer able to use 1920x1080 HiDPI on my TV. :-(
Source: https://forums.macrumors.com/posts/17832271/
Great! I'm assuming the 650M and 750M are supported obviously? Any issues with Integrated graphics vs discrete? Not like I'd use anything other than discrete graphics for 4K output but still.
650M is supported. I have not tested 750M, but if it uses the same driver, it should be supported as well.
Integrated vs discrete graphics?
On 13" rMBP, 4K works fine using my patch, driven by Intel graphics.
On 15" rMBP, external displays seem to always be driven by the discrete GPU. I don't think you can drive an external monitor with the integrated GPU.