Retina 5K iMac is going to lag like crazy

[Gav Mack]

You don't actually know that and Apple engineered a display chip to compensate for all those extra pixels.

A stop gap engineering job it seems so far - seems like they are over-clocking two DisplayPort 1.2 feeds from the GPU to the mst to drive both halves of the display. Hence why it can't be used in target mode as a display only any more.

Something with the broadwell cpu and its Intel chipset update for next years retina iMac that I expect to be engineered properly with the return of target mode with probably DisplayPort 1.3 type connections to the gpu.

 

[Serban]

maybe Apple designed chip is better than DisplayPort 1.3

 

[Gav Mack]

maybe Apple designed chip is better than DisplayPort 1.3

1.2 simply doesn't have the bandwidth even aggregated so they've gone into hod rod dragster mode with some computer nitrous till 1.3 is ready

 

[Serban]

apple designed chip has 1.4

 

[SchneiderMan]

1.2 simply doesn't have the bandwidth even aggregated so they've gone into hod rod dragster mode with some computer nitrous till 1.3 is ready

That's not true. If you've seen the iFixit teardown, The display data cable is larger than the non-Retina display iMac data cable. I'm no expert, but I don't think that it's using DisplayPort to connect to the logic board.

 

[xVeinx]

Maxwell is energy efficient because of clever means of powering down unused portions of the silicon. This was already proven in a couple reviews. If you start running OpenCL applications that are using the machine to it's potential, the power consumption differences are minimal. Also, the memory interface is still 512 in the M version of the core I believe, so memory bandwidth will be better at the ultra-high resolution compared to what nvidia can achieve (which is why the 290 was able to best the 780 and be very close to the maxed out 780 ti at 4k, etc.). I don't think the AMD processor was a bad choice in this case.

 

[EnderTW]

A stop gap engineering job it seems so far - seems like they are over-clocking two DisplayPort 1.2 feeds from the GPU to the mst to drive both halves of the display. Hence why it can't be used in target mode as a display only any more.

Something with the broadwell cpu and its Intel chipset update for next years retina iMac that I expect to be engineered properly with the return of target mode with probably DisplayPort 1.3 type connections to the gpu.

It's not mst. I think anandtech broke it down. It's driving a native single panel.

This is amazing. As there are currently no single 4k displays. I think this is due to apples tcon chip that's able to do this.

 

[Gav Mack]

That's not true. If you've seen the iFixit teardown, The display data cable is larger than the non-Retina display iMac data cable. I'm no expert, but I don't think that it's using DisplayPort to connect to the logic board.

I have seen the ifixit tear down and I can't see you can say that's not true. A mechanical tear down is one thing I use ifixit and technicians guides all the time - how it actually works is another. When chip works and anandtech publish their findings we will find out.

What we do know for sure now is a pair of standard DisplayPort 1.2 channels aggregated provides just enough bandwidth for 4k but well short for 5k.

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It's not mst. I think anandtech broke it down. It's driving a native single panel.

This is amazing. As there are currently no single 4k displays. I think this is due to apples tcon chip that's able to do this.

We don't know - and until chipworks and anand do their detailed reviews and not one shown at the event we'll find out just how amazing it is. I will probably say ingenious stop gap!

 

[johnnyturbouk]

Right - NO COMPUTER can play in 5k --- but sure as hell 12k works already....

Proof? here you go, sir:

https://www.youtube.com/watch?v=UQYU4mNP_a4

https://www.youtube.com/watch?v=U2-Go96dDZ8

You are welcome

Jonny Ive would burst a testicle looking at all those wires, and the thickness of that beast - forget it, apple's motto: we will give you an intel integreated gpu- and you should be thankful of it!

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Lag? In what? Games? Very small subset of customers buy an iMac for games. I hope at least.

Have you spoken to all 'said' customers on their particular usage? -
Gaming comes in much variety from online tetris, angry birds, to the hard core extremers!

 

[johnnyturbouk]

I'd bet on Apple, honestly. They've learned a lot from the previously-released hardware, surely?

I'm going to bet on Apple, personally. If it doesn't perform, it's easy to return to the store.

Normally despite all the bitching and moaning after a new product release - i am more than happy to be one of the first guinea pigs - e.g got every post 3GS iphone on release day. After the 1st rMBP and ipad3 - i felt a little betrayed, sold the mbp when gen too came out. Finally sold my ipad 3 - thank god - it never faired to well with graphic heavy games/videos, multiple apps, the ipad-air so much superior.

I just have a strange gut feeling that this imac will be plagued with issue, and in a few years when graphics applications improve and 4/5K content is finally more commercially available- i fear this machine will struggle. I could be wrong and certainly am pleased others are willing to pull the trigger and go for this model - good luck!

Well there goes my money; I'll stick with my existing iMac thanks.

No one is going to buy this iMac except the uninformed and stupid.

Apple going with this GPU with this display is the biggest mistake they've ever made.

A very informed remark!

I certainly have my reservations about this machine and have decided to await the skylake imac; as this will be a couple of generations on, and hopefully will include a better gpu proven to run such high pixels, also: tb3, pci-ex-3, Usb 3.1, hdm-2, etc - but i certainly would not consider anyone buying this machine either stupid or informed.

I'm hoping I don't have to find out they haven't learned in 2015/17. It's one of those cutting edge Macs that AppleCare is a necessity rather than an option in my humblest..

Best reply of the thread - apple care for these would be a prerequisite.

You don't actually know that and Apple engineered a display chip to compensate for all those extra pixels.

That would be quite interesting and explain the choice of the gpu

A stop gap engineering job it seems so far - seems like they are over-clocking two DisplayPort 1.2 feeds from the GPU to the mst to drive both halves of the display. Hence why it can't be used in target mode as a display only any more.

Something with the broadwell cpu and its Intel chipset update for next years retina iMac that I expect to be engineered properly with the return of target mode with probably DisplayPort 1.3 type connections to the gpu.

Good point, but i though TB3 was coming in skylake in 2015. Correct me if i am wrong, i though the next gen macbooks will be braodwaell, q2/3 2015, followed by skylake for desktops q3/4 2015.

Doing it right will require waiting until DisplayPort 1.3 in Thunderbolt 3 on Broadwell’s successor, Skylake, which isn’t supposed to come out for at least another year — and Intel is even worse at estimating ship dates than I am, so it’s likely to be longer. [...]

I’d estimate — granted, I’m wrong a lot — that Apple won’t ship a standalone 5K display until at least 2016, and it won’t work with any of today’s Macs, including the 2013 Mac Pro.

link

 

[inhalexhale1]

I'm never ever buying a rev. A iMac from Apple again. And based on the company's trackrecord this one is going to be the mother of all rev. A disasters.

Haha, that's a little extreme. But I do feel you on the revA wariness. I was not happy with the rMBP revA at all, but Apple replaced mine (with an updated model!), so at least they stand behind the product.

 

[Pressure]

I have seen the ifixit tear down and I can't see you can say that's not true. A mechanical tear down is one thing I use ifixit and technicians guides all the time - how it actually works is another. When chip works and anandtech publish their findings we will find out.

What we do know for sure now is a pair of standard DisplayPort 1.2 channels aggregated provides just enough bandwidth for 4k but well short for 5k.

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We don't know - and until chipworks and anand do their detailed reviews and not one shown at the event we'll find out just how amazing it is. I will probably say ingenious stop gap!

It has a single TCON (which the ifixit teardown clearly shows), so yes, we can definitively say that this is a single tile and not multi tile monitor.

 

[Gav Mack]

Normally despite all the bitching and moaning after a new product release - i am more than happy to be one of the first guinea pigs - e.g got every post 3GS iphone on release day. After the 1st rMBP and ipad3 - i felt a little betrayed, sold the mbp when gen too came out. Finally sold my ipad 3 - thank god - it never faired to well with graphic heavy games/videos, multiple apps, the ipad-air so much superior.

I just have a strange gut feeling that this imac will be plagued with issue, and in a few years when graphics applications improve and 4/5K content is finally more commercially available- i fear this machine will struggle. I could be wrong and certainly am pleased others are willing to pull the trigger and go for this model - good luck!



A very informed remark!

I certainly have my reservations about this machine and have decided to await the skylake imac; as this will be a couple of generations on, and hopefully will include a better gpu proven to run such high pixels, also: tb3, pci-ex-3, Usb 3.1, hdm-2, etc - but i certainly would not consider anyone buying this machine either stupid or informed.


Best reply of the thread - apple care for these would be a prerequisite.


That would be quite interesting and explain the choice of the gpu



Good point, but i though TB3 was coming in skylake in 2015. Correct me if i am wrong, i though the next gen macbooks will be braodwaell, q2/3 2015, followed by skylake for desktops q3/4 2015.

link

I stand corrected - but tb2 does support aggregation and the new Intel chipset which comes with broadwell carries more PCIe lanes than haswell as well as usb 3 built in. I wonder what they will utilise those extra lanes for?

Plus Intel's roadmap has stalled there's no broadwell yet, yields not good enough and haswell e and EP aren't here yet either. Skylake will be late, Apple have already been held up enough waiting for Intel as it is!

The choice of the GPU was always going to be AMD after the Mac Pro went that way and they jumped on the opencl ship to accelerate FCPX etc instead of licensing CUDA from Nvidia. Nvidia apparently have upped their game with more recent designs when it comes to opencl. Problem with both AMD and Nvidia is they need to shrink their silicon from 28 microns to make the dies smaller, faster and cooler but Apple are hogging all of TSMC's foundries for the AXX parts for iOS cos they don't want to rely all on Samsung! Therefore indirectly and ironically - we are persisting with hot GPU's thanks to Apple lol!

If you want to check out more about the both GPU architectures, 4k etc with regards to OS X - the Mac Pro forum here and posts from MacVidCards in particularand the netkas.org forums. They have been patching nvidia and AMD cards to work in the old towers with boot screens and have some very detailed info about them and how OS X supports these higher resolutions. Tutor in the MP forum has forgotten more about cuda than most of us know and rigs that are worth a look on his monster thread.



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It has a single TCON (which the ifixit teardown clearly shows), so yes, we can definitively say that this is a single tile and not multi tile monitor.

But have they achieved that by bonding a pair of overclocked DisplayPort pipes I wonder?

 

[DannyGGG]

A 5K monitor with a free computer, kinda awesome. Even I could aff.. no wait, never mind.

Well, maybe next year *pout*

That would be a great point if you could use it as an external monitor, but no. Stuck with using its own internals as the computer.

 

[xanadux]

Yes? 5k resolution spread out across a 27" panel you could probably still see pixels if you get close enough.

I went to the Apple Store yesterday, and had taken a very close and careful look at the screen. Sadly, I cannot see those pixels.
There must be something wrong with my eyes.

 

[tillsbury]

But have they achieved that by bonding a pair of overclocked DisplayPort pipes I wonder?

That's what the Apple guy confirmed by tweet in the other thread...

 

[houkouonchi]

Right - NO COMPUTER can play in 5k --- but sure as hell 12k works already....

Proof? here you go, sir:

https://www.youtube.com/watch?v=UQYU4mNP_a4

https://www.youtube.com/watch?v=U2-Go96dDZ8

You are welcome

Putting 3 4k displays together and causing it 12k is pretty deceptive. I wouldn't even call that 12k and that is 4 graphics cards.

5k = 14.75 megaxpiels
3x4k = 24.88 megapixels

It's less than double.

12k would be > 74.65 megaxpiels which is 3x what was shown in that video. Huge difference.

 

[iSayuSay]

Think you have to upgrade to M295X for any video work.

Still a good price when Dell 5K monitor alone is expected to be around $2,500.

Yeah well except you cannot connect the 5K display into anything but the iMac itself.

 

[OurDarkness]

Putting 3 4k displays together and causing it 12k is pretty deceptive. I wouldn't even call that 12k and that is 4 graphics cards.

5k = 14.75 megaxpiels
3x4k = 24.88 megapixels

It's less than double.

12k would be > 74.65 megaxpiels which is 3x what was shown in that video. Huge difference.

Precisely.

 

[kwijbo]

What we do know for sure now is a pair of standard DisplayPort 1.2 channels aggregated provides just enough bandwidth for 4k but well short for 5k.

This is incorrect. DP 1.2 provides 17.28 Gb/s bandwidth; the resolutions in question require the following:

3840*2160*24*60 = ~11.9 Gb/s
5120*2880*24*60 = ~21.2 Gb/s

So DP 1.2 has plenty of bandwidth for 4k while 5k is about 23% over the limit of a single connection. No overclocking needed in the case of 2 DP 1.2 connections for 5k.

After looking at iFixit's teardown some more we see that in the non retina iMac Apple uses a standard implementation 40-pin eDP connector while the riMac connector has 60 pins. My crude guess, Apple is either:

1. "Extending" the DP 1.2 standard to reach the bandwidth they need. The Parade Tech DP663 TCON, which it seems the DP665 in the riMac is based on, has 4 lanes with 2.7 Gb/s per lane. That's way short of what's needed so Apple simply added the lanes they needed knowing they don't need to adhere to a HW standard since it doesn't need any compatibility outside of their own. Hence the increase in pins from 40->60.

2. The DP665 is custom designed to handle HBR2 speeds per lane and take care of aggregating the separate streams, so it's essentially 2 std DP 1.2 feeds. DP 1.2 is 20 pins each * 2, plus the other 20 of a standard eDP connection gives us the total of 60.

 

[theSeb]

This is incorrect. DP 1.2 provides 17.28 Gb/s bandwidth; the resolutions in question require the following:

3840*2160*24*60 = ~11.9 Gb/s
5120*2880*24*60 = ~21.2 Gb/s

So DP 1.2 has plenty of bandwidth for 4k while 5k is about 23% over the limit of a single connection. No overclocking needed in the case of 2 DP 1.2 connections for 5k.

After looking at iFixit's teardown some more we see that in the non retina iMac Apple uses a standard implementation 40-pin eDP connector while the riMac connector has 60 pins. My crude guess, Apple is either:

1. "Extending" the DP 1.2 standard to reach the bandwidth they need. The Parade Tech DP663 TCON, which it seems the DP665 in the riMac is based on, has 4 lanes with 2.7 Gb/s per lane. That's way short of what's needed so Apple simply added the lanes they needed knowing they don't need to adhere to a HW standard since it doesn't need any compatibility outside of their own. Hence the increase in pins from 40->60.

2. The DP665 is custom designed to handle HBR2 speeds per lane and take care of aggregating the separate streams, so it's essentially 2 std DP 1.2 feeds. DP 1.2 is 20 pins each * 2, plus the other 20 of a standard eDP connection gives us the total of 60.

I am pretty sure that 3840*2160*24*60 is closer to ~14Gbps.

and running a 3840 x 2160 24bpp display at 60Hz already uses over 14Gbps of bandwidth just for display

 

[ddarko]

Retina 5k impressions

I'm writing this on a retina 5k iMac at an Apple store, first time I've seen it in person. It's interesting but there is definitely a slight but perceptible jitter/lag with it. The display is set at best for display mode (looks like 2560x1440) and when loading pages on esp.com, you see image jpg's gradually loading - for a split second you see a quarter of an image, then half, then full. It isn't as buttery smooth as the base 2014 retina Macbook Pro I have at home. I don't know if this slight lag would exist with a higher-spec retina iMac but it's there to my eyes in the base model. There is some sort of almost subconscious lag even scrolling quickly up and down this thread page - it just doesn't have the rock solid smoothness of a retina Macbook Pro.

 

[OurDarkness]

I am pretty sure that 3840*2160*24*60 is closer to ~14Gbps.

3840*2160*24*60 = 11.943.936.000, no?

Where did that number 14Gbps come from?

 

[theSeb]

3840*2160*24*60 = 11.943.936.000, no?

Where did that number 14Gbps come from?

As far as I understand it, to run a 4K 24 bpp display at 60 Hz requires ~ 14 Gbps. I could be wrong, but everything I have read tells me that I am not.

 

[OurDarkness]

I'm writing this on a retina 5k iMac at an Apple store, first time I've seen it in person. It's interesting but there is definitely a slight but perceptible jitter/lag with it. The display is set at best for display mode (looks like 2560x1440) and when loading pages on esp.com, you see image jpg's gradually loading - for a split second you see a quarter of an image, then half, then full. It isn't as buttery smooth as the base 2014 retina Macbook Pro I have at home. I don't know if this slight lag would exist with a higher-spec retina iMac but it's there to my eyes in the base model. There is some sort of almost subconscious lag even scrolling quickly up and down this thread page - it just doesn't have the rock solid smoothness of a retina Macbook Pro.

I have just visited http://www.esp.com and it seems that the images fade in. The fade in is gradual and smooth in my laptop. Can you test it on a different riMac?