iMac 5K and DP issue

[BERLY]

Hello,
Question to iMac 5K users.
I just went from a MacPro 2009 to a new iMac 5K i9 (the most powerful with 64GB of RAM).
In the DP sequence window (9.5 or 10), there is a high latency in the display, which makes any editing work tedious in this window. Even with two or three tracks only and zero plugins.

MOTU TECH says to me:

This is certainly due to the 5K monitor. DP is just not entirely written with these 5K monitors in mind. We are hopefully making improvements to this in the future. But I think your problem boils down to the redraw speeds.

Indeed, when I send the DP screen to an external FullHD monitor, I have absolutely no latency problem.
I was wondering if many of us suffered from this problem because I can't find anything about it on the forums. I wonder if MOTU is right to incriminate DP writing at this point or if my system would have another problem.
So if you have an iMac 5K and work on DP, do you have this problem of display latency in the Sequence window?
Thank you
Best regards,
Christophe

[mikehalloran]

Well, they aren't always right. It's not the 5K monitor. It's Apple's default 10bit Color Profile. Changing to anything else makes the issue go away.

viewtopic.php?f=1&t=66601&p=566049&hili ... le#p566049

A workaround? Yes but, till the issue is fixed it... uh... works. Ain't just DP. Finale and other apps can exhibit this behavior.

You don't say what GPU you have, 580 or Vega 48?

iMac Pros have a choice of much beefier GPUs—all higher performance than the best offered in the i9. I suspect that's why I've never seen this issue.

[BERLY]

Hi Mike,

You don't say what GPU you have, 580 or Vega 48?

I have the Vega 48
Thanks
Christophe

[BERLY]

You're wright Mike.
if I select a profile other than iMac, for example Generic RGB Profile, it works! THANK YOU !.
Best regards
Christophe

[HCMarkus]

I love happy endings.

BERLY, it would be great if you add this info to your MOTU Techlink, or otherwise alert MOTU, so future similar issues others face will be easy resolved.

[BERLY]

That's already done !

[mikehalloran]

You're very welcome. The real thanks belongs to this board and those who share their knowledge so that we all learn—and James for providing a place to do this. I learned it here, too.

Surprised to see that you have the Vega 48. Apparently, the Mac OS is writing checks that iMac GPUs can't always cash.

This isn't the first time for something like this. Mac OS 10.8.2 exposed a firmware bug in many ATi GPUs—never fixed but OS 10.10 finally wrote around it while other companies including MOTU rewrote certain protocols to avoid Audio MIDI Setup from crashing our Macs if left open too long. Guess how I know?