No new Thunderbolt Display?

[Clum]

Was half expecting to see a 5K one alongside the iMac.

 

[Deleted member 651465]

Thunderbolt 2 cannot handle the bandwidth of a 5K display.

 

[Tunney]

That doesn't sound plausible. They've managed to squeeze 4K @ 60Hz out of HDMI!

 

[McBain]

Disappointed in this

 

[MagicBoy]

5K requires DisplayPort 1.3. Standard only got announced a month ago : http://www.vesa.org/uncategorized/vesa-releases-displayport-1-3-standard/

Also :

We don’t expect to see DP 1.3 support baked in to any GPUs in the near future. HDMI 2.0 has been out for over a year, and neither AMD or Nvidia supports it yet — though that could change in the very near future. Even so, we expect some lag — AMD has historically been more aggressive than Nvidia with DisplayPort, but has yet to announce plans for DP 1.3 — the company’s just-launched Tonga GPU sticks with DP 1.2.

AMD might refresh its products more quickly depending on what Apple intends to do with the Mac Pro — that system relies heavily on Thunderbolt for connectivity, and DisplayPort 1.3 offers more options for transferring high speed data across the Thunderbolt bus. It’s not impossible that GCN 2.0 could add DisplayPort 1.3 early in the cycle — but without any monitors to support the standard and no word on when GCN 2.0 might actually ship, don’t expect near-term support.

Apple did say in the keynote that they had to create they're own custom controller for the display. Odds are it's using a proprietary connection which is fine in the iMac as it's internal.

 

[teknokid]

Surely they could at least bring out a 4k display though? DP1.2 works fine with that @60hz I believe

 

[Somnambulist]

Apple tend to do things on their terms - traditionally going Retina has meant a doubling of the existing pixel count of a device (unless the size of the screen was altered ala the iPhone 5/5S and iPhone 6/6Plus) since this probably makes the scaling Retina uses easier to implement - I expect they'll be quite happy to only release a standalone 5K Retina Display once there's a Thunderbolt version capable of handling it, which means not any time soon. The Apple store has 4K monitors from other manufacturers on there (presumably for the Mac Pro crowd) and will no doubt keep doing so until they offer their own alternative.

 

[Somnambulist]

Clever people on Reddit:

For those wondering, the current laptops wouldn't be able to do external 5K: 5120x2880 = 14745600 pixels. At 4 bytes per pixel, that is 58,982,400 bytes (~60 MB) on the display. Refresh at 60 fps, 602 = 3600 Mbytes / sec of data bandwidth to run the display. That's 28.8 Gbits/sec to run the 5K display, more than Thunderbolt can offer at 20 Gbits/sec

The ATi chips in the new Retina iMac have two dedicated DisplayPort 1.2 channels going to the display. That's how they're pulling it off -- custom hardware.
You're not easily going to be able to bond two Thunderbolt 2 ports together for an external display (again, it'd be completely custom hardware). If Thunderbolt 3 offers enough bandwidth over a channel, we'll see external displays. Until then? Nope.

I don't think the difference between 4K and 5K is truly appreciated.
4K = 3840x2160 = 8,294,400 pixels
5K = 5120x2880 = 14,745,600 pixels
That's nearly 2x the pixels, despite only going up by "1K".

 

[Arthur17]

Clever people on Reddit:

Not that clever! Do they not realise that ATI stopped making graphics cards over four years ago? The new Retina iMac has AMD graphics.

 

[MagicBoy]

Not quite so clever. Thunderbolt 2 supports DisplayPort v1.2 which won't do 5K, so it's a moot point what the bus speed is...

 

[Tunney]

Pretty much every MacBook Pro and Mac Pro has two Thunderbolt ports, so why not run the connection off two cables? That used to be the solution with DVI.

 

[Somnambulist]

Pretty much every MacBook Pro and Mac Pro has two Thunderbolt ports, so why not run the connection off two cables? That used to be the solution with DVI.

The ports only go to a single bus inside the machine on everything but the Mac Pro, which IIRC has 3 buses over 6 ports, but even then...

It may be possible to use two DisplayPort 1.2 or Thunderbolt 2 cables to power a 5K display, but only if the GPU could treat each port as its own full-bandwidth DisplayPort 1.2 channel, the sum of which represented one logical display, and had the panel combine and properly sync the two at the other end.1 I don’t think any of the current Macs can do this, including the Mac Pro — MST to run 4K panels at 60 Hz only seems to be supported within individual ports, not spanned across two.

http://www.marco.org/2014/10/16/retina-imac-vs-mac-pro