Dell P2715Q and P2415Q 4K IPS Displays

[siqueiros]

Of course when you scale, the PPI of the display doesn't change, just the size of text and UI elements change. At 2560x1440 on a 4K display it makes things look like the size of a desktop on a 122PPI display but is still rendered on the display at the full 185PPI.

Normally, upscaling a 2560x1440 desktop on a 4K display would look fuzzy and unusable, but Apples scaling algorithm first renders the desktop at double the resolution allowing it to take advantage of retina double-pixel artwork and icons before down-sampling to match the displays native rez. Thus a 2560x1440 setting is rendered in the frame buffer at 5120x2880 before being down sampled to 3840x2160. This provides incredible sharpness compared to basic upscaling. And I believe rasterized text is always rendered at native resolution.

So I think people should find out what size they like their text and UI at, then buy the biggest 4K display they can, and scale the desktop to archive that desired size. For some people, 100PPI might be most comfortable. For others 125PPI. I even work at 165PPI (native 4K on my 27" display) when editing photos.

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This is only true at "best for display" (true pixel doubled retina setting). Scaled resolutions do not work that way... As mentioned above scaled desktops are first rendered at double pixel resolution (including image content) and then down sampled to native display resolution. You can verify this by setting your desktop to a scaled setting (eg 2560x1440) and taking a screen capture... You'll see the image is twice the pixels of what you set it to (5120x2880).

If you want pixel perfect image display, you need to use "best for display" or native rez.

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There's nothing wrong with the cables Dell provides. Don't waste your time unless you think you may have a bad cable.

Very informative, useful and interesting post, thank you! Let me to ask about a couple question. Will am i wrong, if we say that Retinasationing or HiDPisation of any monitors is just operating system algorithm, not display functionality or possibility. Monitors just add more pixels for supporting bigger resolution and that all what display manufactures do. I mean there is no any magic technology at the display side, all job do programmatically by the OS.
Or i am totally wrong? Is the classic 1440p monitor, not 4K/5K, also to show the sharp text and UI and became Retina if we use res twice less than native, so then OS be able to 2x and make retinazied.?

 

[VirtualRain]

Very informative, useful and interesting post, thank you! Let me to ask about a couple question. Will am i wrong, if we say that Retinasationing or HiDPisation of any monitors is just operating system algorithm, not display functionality or possibility. Monitors just add more pixels for supporting bigger resolution and that all what display manufactures do. I mean there is no any magic technology at the display side, all job do programmatically by the OS.
Or i am totally wrong? Is the classic 1440p monitor, not 4K/5K, also to show the sharp text and UI and became Retina if we use res twice less than native, so then OS be able to 2x and make retinazied.?

Thanks.

The magic is a combination of HiDPI displays, and an OS that can utilize it... Like iOS or OS X that come with pixel-double artwork and superior scaling algorithms to enable retina mode sharpness. Size doesn't matter... Just DPI... iPhones being a good example of low res screens (iPhone 4 was just 960x640) offering incredible DPI (300+ PPI) to deliver retina sharpness.

 

[asus]

This is only true at "best for display" (true pixel doubled retina setting). Scaled resolutions do not work that way... As mentioned above scaled desktops are first rendered at double pixel resolution (including image content) and then down sampled to native display resolution. You can verify this by setting your desktop to a scaled setting (eg 2560x1440) and taking a screen capture... You'll see the image is twice the pixels of what you set it to (5120x2880).

If you want pixel perfect image display, you need to use "best for display" or native rez

Thanks, I didn't know that, I was sure that in every scenario other then native display resolution, UI and text is scaled and photo/video is 1:1.
I don't actually own OS X device, I want to buy something to use it with 4K display because I don't like how windows handle scaling. So still learning

So then, when you connect mbpr to this dell, best for display option in menu is 1080 HiDPI or native 3840x2160?
And if it's first, that way I'd have scaled 1:4 UI and media will be 1:1 4k?
Because it would be pointless to play 4k video on a 4k display and to miss out 75% of information.


EDIT:
This guy said that at 1440p you also get scaled UI and 1:1 video for apps that support it, and there is an example of it in video.
http://youtu.be/KUvphmy0v2k

More confused now

 

[siqueiros]

So then, when you connect mbpr to this dell, best for display option in menu is 1080 HiDPI or native 3840x2160?
More confused now

For P2715Q is 1080, but it "look like 1080", it's 3840x2160 actually.

 

[VirtualRain]

EDIT:

This guy said that at 1440p you also get scaled UI and 1:1 video for apps that support it, and there is an example of it in video.

http://youtu.be/KUvphmy0v2k



More confused now

It is confusing because there is a lot of misinformation out there. He is wrong. There is no way to render content at 1:1 when scaled because of the non integer scaling factor and down sampling. It only works at "best for display" which is a simple 2x scaling factor where pixel doubling can be ignored for image/video content.

If you run at native 3840x2160 and load a 1920x1080 video, you can zoom to 100% and it will consume exactly 1/4 of your screen with 1 video pixel = 1 display pixel.

If you run at 1920x1080 HiDPI "Best for Display" retina scaling, everything is rendered at double resolution. There is no down sampling like there is on a scaled setting. Retina aware apps will not double the resolution of your content so your 1080p video still uses 1/4 of your screen at 100% with 1:1 pixel mapping. Non-retina aware apps will actually double the size of your content so your 1080p video would consume the full display at 100%. Strangely Apples own Preview is buggy and will sometimes do it either way.

Now let's say you're running at 2560x1440 on a 4k display (1.5x scaling) and load a 1920x1080 video... At 100% zoom the video takes up a big chunk of the display... Not 1/4 as before. That's because like everything else on your desktop it first gets doubled in size so the whole desktop is 5120x2880 and your video would effectively be 3140x2160 (you can confirm this by looking at a screen shot). Then the whole desktop, including your video is down sampled to the native display resolution. And your video will be down sampled with it so its actually being rendered with about 2880px instead of 1920.

Anyone can test this using screen shots with content of known sizes.

 

[dagamer34]

I picked up a Dell P2715Q today to pair with my iMac with Retina 5K Display (upgraded CPU/GPU). Running at scaled "looks like 2560x1440" mode without any issues. Good enough for a 2nd monitor while doing software development, and windows remain the same sizes if I drag one to another. It flickered every minute or two for the first 30 min, but hasn't done so since (knock on wood) after I pulled the power cord.

In OS X, if you look closely enough, you can probably tell it's not quite as sharp as the built-in display, but that's no different than scaling modes on other Retina Macs. Running Windows 10 in Parallels though, you absolutely couldn't tell it wasn't native. It's amazing.

Only disappointing thing is that I can't get another display and have one to both my left *and* right. Haha.

 

[campyguy]

I just had an OMG moment...

A couple of things happened today. A friend got stuck in Seattle traffic and bailed on me, and my GF asked me to move some of my "stuff" (in my home office, no less)...

Long story, TL;DR version:

I own a late 2013 rMBP with the discrete 750M (which this post is about) and a 2012 Mac Mini Server - each connected to one of two P2715Q monitors, and each mounted to a Herman Miller Flo arm.

In my haste to make my GF happy (for now) I mistakenly connected both Dell-supplied mDP-to-DP cables leading to the two monitors to my rMBP, instead of connecting my TB array, then powered on both my rMBP and Mini. Nothing showed up on my Mini, but both P2715Qs reflected an extended Desktop from my rMBP. WTH?

Cutting to it, after installing 10.10.3, my rMBP is showing an extended - not mirrored - Desktop on the integrated display and the two P2715Q displays, up to 4k on both displays, at 60Hz, in either portrait or landscape mode. They're both up and running now, in portrait mode, in HDPI at 1080x1920 and I watched two 4k videos - one on each P2715Q, simultaneously, at 3840x2160 (because I can now!).

I can "toss" an application window from display to display (using Spectacle.app), switch applications, and use different resolutions on either Dell monitor. And, my rMBP isn't overheating! No lag, no hesitations, no stuttering. No crap!

FWIW, I also tried a Cable Matters mDP-mDP 1.1a cable, and that worked OK as well. 4k @ 60Hz, but the switching was sloooooooowwww. I'm considering ordering a couple of mDP-mDP 1.2 cables next week. Now, I've got a rMBP with its built-in display powering two 4k monitors - which I couldn't do on 10.10.2, and I can do it at 60Hz on both monitors!

 

[ronjns]

OMG campyguy, that's really cool! I'm planning to get a riMac with two 2415Q but wasn't sure that it'll work but if rMBP can drive two 2715Q @ 60Hz there's little reason a riMac won't.

Can I confirm with you the 15" retina rMBP built-in display is running as well along with the two 2715Q? Thanks!

 

[siqueiros]

It is confusing because there is a lot of misinformation out there. He is wrong. There is no way to render content at 1:1 when scaled because of the non integer scaling factor and down sampling. It only works at "best for display" which is a simple 2x scaling factor where pixel doubling can be ignored for image/video content.

If you run at native 3840x2160 and load a 1920x1080 video, you can zoom to 100% and it will consume exactly 1/4 of your screen with 1 video pixel = 1 display pixel.

If you run at 1920x1080 HiDPI "Best for Display" retina scaling, everything is rendered at double resolution. There is no down sampling like there is on a scaled setting. Retina aware apps will not double the resolution of your content so your 1080p video still uses 1/4 of your screen at 100% with 1:1 pixel mapping. Non-retina aware apps will actually double the size of your content so your 1080p video would consume the full display at 100%. Strangely Apples own Preview is buggy and will sometimes do it either way.

Now let's say you're running at 2560x1440 on a 4k display (1.5x scaling) and load a 1920x1080 video... At 100% zoom the video takes up a big chunk of the display... Not 1/4 as before. That's because like everything else on your desktop it first gets doubled in size so the whole desktop is 5120x2880 and your video would effectively be 3140x2160 (you can confirm this by looking at a screen shot). Then the whole desktop, including your video is down sampled to the native display resolution. And your video will be down sampled with it so its actually being rendered with about 2880px instead of 1920.

Anyone can test this using screen shots with content of known sizes.

By the way, what is the "native res" for the rMBP15 and why there is no ability to choose it? I worry, because there is different at Dell P2715Q display control panel which has a last option to use native res, but built-in rMBP retina display not. Because all available resolution of rMBP is has double number pixels when i screenshot destop and look for image size in Photoshop. But Dell has the last one resolution, which is a native, and at this resolution screenshot image size ecual to res. So Dell P2717Q has 3840x2160 native res, but built in retina displays all available deskop res is double, what is it native res, how does we know?

 

[campyguy]

Can I confirm with you the 15" retina rMBP built-in display is running as well along with the two 2715Q? Thanks!

No, but I can confirm it!

More to the point, my GF didn't get back until after 1 am and was a bit miffed when I told her that I didn't even miss her! Admittedly, I had to reconfigure my workspace again when I realized I can use both displays with my rMBP! Yes, the rMBP display works alongside the two P2715Q monitors - no hassles, no crashes, no lagging/choking/hesitations. So, so happy with this (and Apple Engineering, for once in a long time)...

One more clarification, I also tried daisy chaining one display to the second and both Dell displays were mirrored. Each display is connected via the Dell-supplied mDP-DP cables, with one cable installed in each of my rMBP's TB2 ports - I'm using the two displays in Portrait mode and like the locking feature of the Dell cables (see the attached screenshot of my Displays Pref Pane. This set up was not working at all before my 10.9.3 install.

 

[JTToft]

By the way, what is the "native res" for the rMBP15 and why there is no ability to choose it? [...] So Dell P2717Q has 3840x2160 native res, but built in retina displays all available deskop res is double, what is it native res, how does we know?

- Just look it up in Apple's specifications: 2880x1800.
As for getting that full native resolution, hold down Option while clicking the "Scaled" bullet in display preferences. If that doesn't do it, SwitchResX will.

 

[VirtualRain]

By the way, what is the "native res" for the rMBP15 and why there is no ability to choose it? I worry, because there is different at Dell P2715Q display control panel which has a last option to use native res, but built-in rMBP retina display not. Because all available resolution of rMBP is has double number pixels when i screenshot destop and look for image size in Photoshop. But Dell has the last one resolution, which is a native, and at this resolution screenshot image size ecual to res. So Dell P2717Q has 3840x2160 native res, but built in retina displays all available deskop res is double, what is it native res, how does we know?

Apple will not show native resolution on their retina displays by default... Perhaps they feel things would be too small for most people? As someone else said, hold Option or get SwitchResX or there is a similar Display menu bar widget in the Mac App Store that should do it (but I forget the name of it - search for "Display").

 

[edry.hilario]

http://9to5mac.com/2015/04/12/os-x-...12-inch-macbook-adds-5k-dell-for-mac-proimac/

Apple will not show native resolution on their retina displays by default... Perhaps they feel things would be too small for most people? As someone else said, hold Option or get SwitchResX or there is a similar Display menu bar widget in the Mac App Store that should do it (but I forget the name of it - search for "Display").

so does the p2715q now work well in osx? like boot screens and all that? Im just wondering because apple released an update.

This article make seem like it does. Can anyone confirm? at least for the mac pro?

ps. the dell 5k display is now officially supported too. Which I probably will eventually get if it comes down in price.

 

[iamfredrik]

My P2415Q won't wake up after my rMBP has slept overnight. I'm using the dp cable that came with the monitor and I have Yosemite 10.10.3 installed. When I press the menu button on my P2415Q, it shows a text where it says that there is no signal coming from my computer. Is there any way to fix this or did I receive a lemon?

Edit:
I have to power down everything for 2 minutes to get the signal back. Seems to happen after rMBP has been in deep sleep. Will disabling hibernation on rMBP fix the problem?

Edit 2:
I could reproduce the problem with the following steps.
1. Power off the Dell and unplug the power cord.
2. Put rMBP in sleep using battery power only.
3. Wait half an hour before powering back on.

Edit 3:
Standbydelay is 10800 (3 hours) so hibernation can not be the cause?

 

[campyguy]

ps. the dell 5k display is now officially supported too. Which I probably will eventually get if it comes down in price.

I saw your post and am reading up on what's available for options right now. I'm looking to buy a riMac later this year and considered a Dell 5k display, but now - for that kind of cash - I'm thinking I'd rather buy a second, low-end riMac and use it for a second display (in Target Display Mode) if that's possible later this year, at least I'll investigate it. 10 days ago I couldn't drive two 4k monitors via DP with my rMBP but now I can at 60Hz. For $100 more I'd rather have an riMac attached to another high-end riMac, unless the Dell's price comes down! Just saying!

 

[VirtualRain]

http://9to5mac.com/2015/04/12/os-x-...12-inch-macbook-adds-5k-dell-for-mac-proimac/

so does the p2715q now work well in osx? like boot screens and all that? Im just wondering because apple released an update.

This article make seem like it does. Can anyone confirm? at least for the mac pro?

Boot screens will require a firmware update as that's handled by EFI. No idea if Apple will bless us with that... Would be nice but not counting on it.

I haven't been having any OS X problems on my nMP since I started the 10.10.3 beta a voupe of months ago.

It sounds like the main improvements are for true 4K displays like the LG and MacBook support. So if either of those are near and dear to you, it will be good news.

 

[theSeb]

Boot screens will require a firmware update as that's handled by EFI. No idea if Apple will bless us with that... Would be nice but not counting on it.

I haven't been having any OS X problems on my nMP since I started the 10.10.3 beta a voupe of months ago.

It sounds like the main improvements are for true 4K displays like the LG and MacBook support. So if either of those are near and dear to you, it will be good news.

How can Apple claim support for these monitors if you guys don't have boot screens. That seems odd to me. Still, I am tempted to pick up one, or two, of these to use with my nMP. I'll keep the 24" ACD for boot screens if I have to.

 

[siqueiros]

Thanks.

The magic is a combination of HiDPI displays, and an OS that can utilize it... Like iOS or OS X that come with pixel-double artwork and superior scaling algorithms to enable retina mode sharpness. Size doesn't matter... Just DPI... iPhones being a good example of low res screens (iPhone 4 was just 960x640) offering incredible DPI (300+ PPI) to deliver retina sharpness.

I see, thanks again. It'is like Adobe Photoshop image size dialog box, we need enough numbers of pixels to be able to print good and sharp pictures at desire size. If there is enough numbers pixels to fill one inch square with about ~300 PPI or more, then printed image at paper will be at nice quality, if it less then we must to print on the smaller size of paper or going to resample or scale the image, when the software use some algorithm to add more pixels to the image.
So, there is still 15" size monitors at the market, which usually had 1024 by 640 default res, and if manufacture double it working pixels multiplying its to the 2040 x 1280, then those displays also will be retina, or HiDPI, isn't it? If true, it is a pity to me personally that there is no any small size Retina/HiDPI displays.

 

[VirtualRain]

How can Apple claim support for these monitors if you guys don't have boot screens. That seems odd to me. Still, I am tempted to pick up one, or two, of these to use with my nMP. I'll keep the 24" ACD for boot screens if I have to.

Are they claiming to support these monitors? What does "support" mean?

At any rate, the lack of boot screens is not related to the display... it's strictly an Apple EFI thing. As far as I know, no SST 4K display will show a boot screen on any Mac at the moment, but if any Mac supports a 4K SST display at boot, it would be one of the recently released rMBPs which would have the latest firmware... it would be interesting to hear from someone with one of the latest machines if there is boot screen support now.

 

[siqueiros]

Are they claiming to support these monitors? What does "support" mean?

At any rate, the lack of boot screens is not related to the display... it's strictly an Apple EFI thing. As far as I know, no SST 4K display will show a boot screen on any Mac at the moment, but if any Mac supports a 4K SST display at boot, it would be one of the recently released rMBPs which would have the latest firmware... it would be interesting to hear from someone with one of the latest machines if there is boot screen support now.

I am using rMBP15"/10.10.3 and P2715Q as a second display and can confirm that it is seem to be support now, because when i restart machine with lead closed then there is apple logo show. But because i can't to press option with closed lead and have not a external keyboard i can't to say exactlly if i can start with boot screen. Or you are interested of Mac Pro owners?

 

[VirtualRain]

I am using rMBP15"/10.10.3 and P2715Q as a second display and can confirm that there is still no boot screen. Or you are interested of Mac Pro owners?

No interested in hearing from owners of the recently updated 2015 rMBPs.

 

[siqueiros]

No interested in hearing from owners of the recently updated 2015 rMBPs.

mine is late 2014 and it look like show the booting process on the Dell P2715q which connected as a secondary. Later i will try with connected external keyboard with closed lead and report more sure.

 

[edry.hilario]

Dead Pixels

Guys,

SO i got the p2715q in.. it has dead pixels.. i'm obviously returning it. It cannot be unseen. Is this common on these monitors? Are yours dead pixel free? I want to know since I don't want to get a replacement and get the same or other issues. The picture quality is great though.

 

[iamfredrik]

My P2415Q won't wake up after my rMBP has slept overnight. I'm using the dp cable that came with the monitor and I have Yosemite 10.10.3 installed. When I press the menu button on my P2415Q, it shows a text where it says that there is no signal coming from my computer. Is there any way to fix this or did I receive a lemon?

Edit:
I have to power down everything for 2 minutes to get the signal back. Seems to happen after rMBP has been in deep sleep. Will disabling hibernation on rMBP fix the problem?

Edit 2:
I could reproduce the problem with the following steps.
1. Power off the Dell and unplug the power cord.
2. Put rMBP in sleep using battery power only.
3. Wait half an hour before powering back on.

Edit 3:
Standbydelay is 10800 (3 hours) so hibernation can not be the cause?

This seem to be a timing issue with the rMBP. I have a switch that powers down the monitor and rMBP at night, leaving the rMBP in sleep mode on battery power and the P2415Q off without electricity.

There are two workarounds:
1. Keep power on at night. Does not matter if P2415Q is in power saving mode or switched off using the button.

2. Switch off power and completely shut down rMBP at night.

This is not caused by the P2415Q, but a common problem for all monitors connected to the Thunderbolt port:
https://discussions.apple.com/thread/3356740?start=0&tstart=0

 

[wakele]

Guys,

SO i got the p2715q in.. it has dead pixels.. i'm obviously returning it. It cannot be unseen. Is this common on these monitors? Are yours dead pixel free? I want to know since I don't want to get a replacement and get the same or other issues. The picture quality is great though.

I changed my p2415q for a similar reason. There were two groups of pixels that they were not dead, but their color it was lighter than the others. No problems at all with my new screen, Dell replaced it (very good customer service from Dell Spain) and, furthermore, I received the new firmware with it (A01).
I don't think this is a common issue, I am following this thread for some months and not so many complaint about that.