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Dual Dell UP2715K Monitors + Mac Pro = Success!!

Z

zesta

macrumors member
Original poster
Jan 31, 2008
44
5
I didn't see anywhere mentioning if the 2013 Mac Pro supported *2* 5K Dell UP2715K monitors. Apple's site only mentions the ability to support the model.

I have 2 of them, so I figured I would try. I had the first one already working as my main display. When I first connected the second, it showed up as detected by the Mac Pro, but the screen was black. After disconnecting one cable, and getting it to come up at 2560x1440, I plugged the other cable back in, and it came up at full res. So, while only supporting 2x 4K monitors at 60Hz, the Mac Pro will also drive 2x 5K at 60Hz. That is nearly double the pixels.

I have not had a chance to test much with regard to performance or anything.

As a side note, I verified that it does work as a second monitor on a 5K iMac with the m295x, but it makes it reeeaaaallly slooooww for most things. It was also pretty flaky, blinking in and out.

Now, if Apple would just fix the detection at boot, so you can get the boot logo and such, it would be perfect. If you hold "option" at boot for a very long time, you do get a screen, which appears to be at 2560x1440, or something similar.

When I get back from the weekend, I'll test some more. I am not likely to keep this setup, as it eats 2 extra Thunderbolt ports, and I only really have 1 spare.
 
zesta said:
Considering only 2 4K monitors are supported, I seriously doubt 3 5K will work. I am surprised that 2 5K worked. If you would like to buy me one, I will be glad to try 3 ;-)
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haha. Well I mean the mac pro 6 thunderbolt ports. So I thought it would be able to power up 3. But congrats though, to be able to purchase 2 5k. I can't even afford one 5k
 
I really couldn't afford 2 of them either. I actually had 2 of the UP2414Q, which had various issues (particularly the wake up problem). Dell said that the UP2414Q was no longer available, so they sent me the "next best" model, which happened to be the UP2715K. *shrug* I'm not going to complain. The UP2715K is awesome, and is the most "Mac-like" monitor I've seen from Dell. As I said before, I just wish Apple would better support it (boot screen, etc.)
 
zebi said:
Hi Zesta, does this setup work well? Is there any glitching graphics etc? I'm looking at purchasing 2 of 5k screens.
Click to expand...

Nothing so far, but I have not really done much that would push it.

Is there anything specific you would like me to test?
 
After some more testing, I can say that this is not really usable. I started getting some odd artifacts, and some graphical glitching when trying to use both to actually display things. I tested for 60Hz refresh on the second, and it failed.

I am guessing that the graphics cards just can't support the full resolution from the perspective of the outputs that are available. Obviously they are powerful enough to push the data, but the mac pro just was not designed to have 4 nearly 4K displays connected at 60Hz. If there was a way to force 30Hz on the second, it might work.

I don't have a mini-DP to mini-DP cable, so I can't test the second at 4K.

I guess we'll have to look forward to a redesign that supports single-stream 5K+, or maybe even multiple multi-streams.
 
Well apple is claiming three 5k displays on the mac pro. so I guess we'll see what happens? I think indications are strong that this should work.
 
zesta said:
After some more testing, I can say that this is not really usable. I started getting some odd artifacts, and some graphical glitching when trying to use both to actually display things. I tested for 60Hz refresh on the second, and it failed.

I am guessing that the graphics cards just can't support the full resolution from the perspective of the outputs that are available. Obviously they are powerful enough to push the data, but the mac pro just was not designed to have 4 nearly 4K displays connected at 60Hz. If there was a way to force 30Hz on the second, it might work.

I don't have a mini-DP to mini-DP cable, so I can't test the second at 4K.

I guess we'll have to look forward to a redesign that supports single-stream 5K+, or maybe even multiple multi-streams.
Click to expand...

Interesting... thanks for trying... and lucky you for getting a pair of 5K displays!

How are you connecting them? What combinations have you tried?

display_ports.png
 
From the other thread...

"I am now testing with nothing else connected. Both cables for UP2715K #1 are connected to Bus 0. That works fine.
UP2715K #2 is connected one cable to each of the other 2 Thunderbolt buses. It is better than before, so far, but still a little glitchy. 60Hz testing fails. Sometimes there are graphical anomalies, particularly if you move a window from the primary display. The slight progress is encouraging, though."
 
zesta said:
From the other thread...

"I am now testing with nothing else connected. Both cables for UP2715K #1 are connected to Bus 0. That works fine."
Click to expand...

That's interesting. I'm surprised one bus can drive a 5K display.

Can someone more technical tell me how a single TB2 controller can provide the 26Gbps required for a 5K display at 60Hz?
 
VirtualRain said:
That's interesting. I'm surprised one bus can drive a 5K display.

Can someone more technical tell me how a single TB2 controller can provide the 26Gbps required for a 5K display at 60Hz?
Click to expand...

I seem to remember reading something that explained that if you connect a monitor directly to the Mac Pro, that the port switches to DisplayPort-only, and does not use the TB bandwidth. I can't seem to find that info now. Can anyone verify?
 
zesta said:
I seem to remember reading something that explained that if you connect a monitor directly to the Mac Pro, that the port switches to DisplayPort-only, and does not use the TB bandwidth. I can't seem to find that info now. Can anyone verify?
Click to expand...

I posted that. It's an educated supposition and the fact that you're able to get those two monitors to work at all, even erratically, seems to support it.
 
edanuff said:
I posted that. It's an educated supposition and the fact that you're able to get those monitors to work at all, even
Click to expand...

That would explain it. If true, it means each TB port can provide a DP1.2 connection which would thus support 6 full DP1..2 connections. So now I don't understand why both don't work.
 
VirtualRain said:
That would explain it. If true, it means each TB port can provide a DP1.2 connection which would thus support 6 full DP1..2 connections. So now I don't understand why both don't work.
Click to expand...

Well, it just means the TB controller is not the limiting factor, but the GPUs still have limitations.
 
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edanuff said:
I posted that. It's an educated supposition and the fact that you're able to get those two monitors to work at all, even erratically, seems to support it.
Click to expand...

I actually remember reading something about it when the 2013 Mac Pro launched, but I don't recall if it was fact, or supposition at the time.
 
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