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sethmacbookuser

macrumors newbie
Original poster
Mar 14, 2015
20
3
I had assumed that Apple was waiting for the next generation Thunderbolt port to release a standalone Retina Display. My understanding is that the current Thunderbolt 2 and USB 3.1 ports can't transfer data fast enough from a computer to a 5K display. Is the USB-C fast enough? Or is this not the correct way at looking at the question?
 
I had assumed that Apple was waiting for the next generation Thunderbolt port to release a standalone Retina Display. My understanding is that the current Thunderbolt 2 and USB 3.1 ports can't transfer data fast enough from a computer to a 5K display. Is the USB-C fast enough? Or is this not the correct way at looking at the question?

USB Type-C can support DP1.3 which is required for 5K displays, but you also need a GPU capable of DP1.3 and that's not the case with the Core M in the MacBook. Future Mac's with USB-C may get DP1.3 and 5K support, but not this one.

From AnandTech...

Finally, through the use of USB alternate mode functionality, Apple is able to also supply DisplayPort over the Type-C connector. Through the alt mode capability, 1, 2, or 4 lanes of USB 3 data can be replaced with alternate protocols, in this case DisplayPort. The final resolution that can be passed though is implementation specific and isn’t available in Apple’s specifications – but based on Core-M’s capabilities I suspect that Apple has it setup to use 2 lanes, which would allow a maximum of 2560x1440 (WQHD). Meanwhile DisplayPort can also be actively converted to other formats, which is what allows Apple to offer HDMI and VGA through adapters.
 
I presume that the iMac must have a GPU capable of DP1.3 (whatever that is). Does the current Mac Pro? Or any of the MacBooks? I know it's not relevant for practical purposes since without the connector, you can't use a 5K display anyway. But I'm just curious.

USB Type-C can support DP1.3 which is required for 5K displays, but you also need a GPU capable of DP1.3 and that's not the case with the Core M in the MacBook. Future Mac's with USB-C may get DP1.3 and 5K support, but not this one.

From AnandTech...
 
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I presume that the iMac must have a GPU capable of DP1.3 (whatever that is). Does the current Mac Pro? Or any of the MacBooks? I know it's not relevant for practical purposes since without the connector, you can't use a 5K display anyway. But I'm just curious.


Capable? Yes. Implemented? No. DP1.3 requires hardware to support it. Most discrete GPUs in current machines have the power to drive that many pixels but don't have DP1.3 output.
 
I presume that the iMac must have a GPU capable of DP1.3 (whatever that is).

DP1.3 = DisplayPort 1.3. Its a video connector & display communication protocol (like HDMI and DVI). Macs have used DisplayPort 1.1 for years. DisplayPort 1.2 added 4k support and DisplayPort 1.3, which is very new adds 5k.

Both USB-C and Thunderbolt can double as DisplayPort connectors. In the case of Thunderbolt, the DP standards are deeply entwined with the Thunderbolt protocols, and Thunderbolt 2 only supports DP1.2, and will have to wait for Thunderbolt 3 for DP1.3.

USB-C takes a simpler route - just allocating some or all of its physical wires to DisplayPort - and will support DP1.3 as soon as suitable GPUs appear.

Whether a GPU can support a 5k display and whether it has DisplayPort 1.3 are two separate things. The GPU in the new MacBook probably fails on both counts (although according to Apple's specs it can do 4k, just not with the HDMI adapter they offer).

The iMac 5k GPU doesn't support DP1.3, but the GPU can drive 5k pixels and uses some sort of proprietary Apple internal connection to get 5k from the GPU to the display.

The Dell 5k display uses two separate DisplayPort 1.2 cables - each driving half the screen. It will only work on the Mac if someone locks Dell, Apple and AMD in a room and doesn't let them out until they write OS X drivers.
 
It will only work on the Mac if someone locks Dell, Apple and AMD in a room and doesn't let them out until they write OS X drivers.
As a grumpy Mac and 4k monitor user who also happens to be 6'7" 260#, I'll volunteer to be that "someone"... :mad:
 
Is the USB-C fast enough? Or is this not the correct way at looking at the question?
The latter since USB-C is a connector type which has not much to do with the actual protocol. The connector is designed for USB2.0, 3.0, 3.1 gen 1 and 3.1 gen 2. It all depends on what the devices on each end of the cable supports.

Apple is using USB3.1 gen 1 in the new MacBook which is USB3.0 and thus only 5Gbps. Gen 2 is 10 Gbps and although it does support DisplayPort 1.3 you might run into the 10Gbps bandwidth limitation. They are also using an Intel GPU that isn't capable of driving a 5K resolution. The specs tell us it only supports external displays with a resolution of up to 3840x2160. As you can see here there are more components in the chain which is only as strong as its weakest link.

USB is a cheaper alternative to things like Thunderbolt so it is not that strange it won't be able to drive a 5K display at the moment. Those displays are on the high end side of things but that is probably going to change.
 
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