OSX 10.11.1 supports 10 bit color, but .....

[wopbv4]

Finally OSX supports 10 bit/colour (30 bit) colour.
HOWEVER, now the applications are lagging behind.
Capture One 8.3.4 uses the 10 bit colour option, but Photoshop CC does not.

Furthermore, only some displays make use of this option.
To check if your system/display supports 10 bit:
1) About this MAC
2) System report
3) click the Graphics/Displays tab
4) look for Pixel depth, ARGB8888 uses 8 bit, ARGB2101010 uses 10 bit

A good test file to check for 10 bit is:

http://www.imagescience.com.au/kb/getattachment.php?data=MTUyfDEwIGJpdCB0ZXN0IHJhbXAuemlw

If you see banding you are at 8 bit. if the gradient is smooth, it is 10 bit

 

[CSD]

Finally OSX supports 10 bit/colour (30 bit) colour.
HOWEVER, now the applications are lagging behind.
Capture One 8.3.4 uses the 10 bit colour option, but Photoshop CC does not.

<snip>

If you see banding you are at 8 bit. if the gradient is smooth, it is 10 bit

Just to be pedantic, you've not got a true 10Bit workflow. That requires 10bit displays like the HP DreamColor, EIZO ColorEdge, or NEC Spectraview and supported cables with DisplayPort or HDMI 1.3 spec. You also usually also need a FireGL/Quadro card.

 

[Delish]

OSX currently displays 10bit color a bit inaccurate.
this is a AMD 7950, with the U2711 connected with DVI(left screen), and U2713H with displayport(right screen).
Both shows 10 bit color in system profiler, but only the one connected with displayport actually show better graduations.

left connected with DVI, right with displayport. Image posted in first post shown in Preview.app

(when booting windows only the displayport connected screen shows up as 10 bit in AMD catalyst.)

 

[9VIII]

Now that it's a UHD Blu-ray spec 10 bit should be much more prevalent in the coming years.
HDMI 2.0 is going to be the home video standard, don't get a 4K TV without it, and Displayport 1.3 is going to do cool PC stuff like 5K and 120hz 4K.

 

[wopbv4]

Finally OSX supports 10 bit/colour (30 bit) colour.
HOWEVER, now the applications are lagging behind.
Capture One 8.3.4 uses the 10 bit colour option, but Photoshop CC does not.

<snip>

If you see banding you are at 8 bit. if the gradient is smooth, it is 10 bit

Just to be pedantic, you've not got a true 10Bit workflow. That requires 10bit displays like the HP DreamColor, EIZO ColorEdge, or NEC Spectraview and supported cables with DisplayPort or HDMI 1.3 spec. You also usually also need a FireGL/Quadro card.

Indeed, you are right, one needs the full chain.
Apparently the new iMac 5K is the only iMac that support 10 bit, the older iMac do not. Even so, the gamut of the new iMac is not even close to the gamut of an Eizo CG monitor
I have a Mac pro (trash can) with an Eizo CG276 and I can confirm that this combo works.

 

[wopbv4]

OSX currently displays 10bit color a bit inaccurate.
this is a AMD 7950, with the U2711 connected with DVI(left screen), and U2713H with displayport(right screen).
Both shows 10 bit color in system profiler, but only the one connected with displayport actually show better graduations.

left connected with DVI, right with displayport. Image posted in first post shown in Preview.app

(when booting windows only the displayport connected screen shows up as 10 bit in AMD catalyst.)

I am not sure what causes the difference, but what I do know is that my Eizo does not support 10 bit with a DVI cable.
It needs display port cable

 

[mackguyver]

I've got a full 10-bit set up on Windows 10 - Quadro card, Displayport, Dell 10-bit monitor, PhotoShop CC 2015, and well, I wouldn't do it again. The Quadro card is way overpriced compared to GeForce and 10-bit color is just barely noticeable on most photos as they are continuous tone anyways. Calibrating your monitor makes the most difference, followed by having a nice wide-gamut monitor. 10-bit is definitely at the point of diminishing returns.

Good to see that it's finally supported by Apple, though