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iMac Pro Refresh rate on the iMac Pro?

theluggage said:
I suspect that your problem has nothing to do with refresh rate - unlike CRTs, TFT LCDs just don't flicker in time with the refresh rate (try setting the refresh to 30Hz - still no flicker on static images).

Rather, the likely cause is some TFT displays' use of Pulse Width Modulation (PWM) to control the brightness (i.e. they dim the backlight by turning it on and off very rapidly, and adjusting the on:eek:ff ratio). That does cause flicker - especially as you dim the display. "Flicker free" displays use other methods of dimming or use PWM with a very high frequency base - odds are your 120Hz refresh displays, being upmarket, are flicker-free, but PWM and refresh rate are quite separate issues.

I can't find a straight answer on whether the 5k iMac display is technically flicker-free - I haven't noticed any flicker.
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Thanks for the information about "PWM". Are there specific types of monitors that don't have this issue?

Also, I'm interested in whether I can drive an external monitor from my 2017 MacBook Pro 15 inch (Radeon Pro 560)? I've stopped by a few Apple stores and nobody seems to be able to give me a straight answer.
 
sevenall said:
Thanks for the information about "PWM". Are there specific types of monitors that don't have this issue?
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It can be quite hard to find out - http://www.tftcentral.co.uk/ do in-depth reviews on displays which include a test for PWM flicker - and have an in-depth article on it at: http://www.tftcentral.co.uk/articles/pulse_width_modulation.htm#why

sevenall said:
Also, I'm interested in whether I can drive an external monitor from my 2017 MacBook Pro 15 inch (Radeon Pro 560)?
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Yes - you'll need the appropriate USB-C to DisplayPort or HDMI adapter. Lots of threads here on displays.
 
sevenall said:
With all of the GPU power...it's hard to be believe that you can't drive the screen higher than 60hz?! One of the things holding me back from purchasing iMac models is that crummy refresh rate.

Apple has made the move to 120hz on the latest iPad Pro...why not bring this to their desktops?
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William Payne said:
Have you been to an eye doctor? unless you have always had 120hz monitors your entire life I wonder if you either have a problem or if you had this before 120hz monitors became a thing?

I do however wonder if you have a physical problem.
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If you're capable of perceiving the world at 120 hz, then you're going to see flickering from fluorescent lights like houseflies do, and films in a movie theater will appear to stutter instead of showing fluid movement. What's more likely is that as a gamer you perceive the speed of the computer updating your movements at 120 FPS as a lack of input "lag". The same effect could be had by having the game update your input 120 times a second while only rendering every other frame (nVidia cards actually have a setting for this in Windows).

But let's talk about 5K... The only way that you can drive a 5K monitor at 120 HZ (frames per second) is to use dual high-end nVidia cards running in SLI, with lowered graphical settings. That costs $1400 if you're using GTX1080ti cards. Which is ridiculously expensive and overpowered for most user's needs. Not to mention the cooling system that you would need in a PC tower... Much less an iMac chassis. The PC under my desk has dual cards, and it's quite the space heater when I start gaming on it.

And again... Because it needs to be said over and over... Apple in general, and with the iMac Pro in particular, are not focused AT ALL on gaming. They sell design productivity machines. It's only lately that they've jumped on the VR bandwagon, and if you look at the apps they show off, most of them are not games, but 3D design apps and non-game augmented reality. You might buy a Mac to develop games, but you don't buy a Mac specifically to play them. At best, you'll be able to play the newest titles for 12-18 months on a top-end iMac before you'll have to settle for lower graphical settings than you would on a PC.
 
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hmm, to all nay-sayers: once you experience smooth UI (animations, windows, etc) and mouse screen movement in anything above 60Hz, you won't go back to it. Obviously a huge bonus for gamers, but also in "normal" desktop usage, it's amazing.

It's like the old days of windows CE stuttery scrolling via stylus and then the capacitative iPhone screen came out.
The "problem" (if you want to call it this way), is that 90% of the panels in everything are 60Hz, so not enough people have seen and felt the difference to make a critical mass for pushing manufacturing of higher Hz panels.

Technically there's more to it than just the panel, you also need the connection to carry this bandwidth, etc...

On my hackintosh I personally did not switch my 1440p 144Hz TN panel for a 4K 60Hz IPS one.
Yea, looks a bit worse but you get used to it. However the smoothness of 144Hz is something i missed straight away, even on the iMac.
 
sevenall said:
With all of the GPU power...it's hard to be believe that you can't drive the screen higher than 60hz?! One of the things holding me back from purchasing iMac models is that crummy refresh rate.

Apple has made the move to 120hz on the latest iPad Pro...why not bring this to their desktops?
Click to expand...

LG only makes 60Hz 5K panels and only LG makes 5K panels, period. So Apple has no other options. I also expect the internal timing controller is based on DisplayPort 1.2 and that only supports 60Hz at 5K.

Intel has announced an update to TB3 to support DisplayPort 1.4. which will support 8K@60Hz and 4K/5K@120Hz so this should hopefully spur LG (or others) to start making 120Hz 5K displays and Apple will be able to update their internal timing controller to support 120Hz, as well.
 
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4k is OK but 5k is not. The DP1.4 5K 120Hz (or 8k 60Hz) require Display Stream Compression. It means a single DP 1.4 can't transmit 8bit uncompressed signal @5k 120Hz. Since Apple already go 10bit now, and they so care about the still image quality. I doubt if they really want to go this compressed route.

Of course, Apple don't need to follow the standard. Just like they make the 1st 5K iMac when the GPU should only support up to DP 1.2. But they use their "black magic" to "fix" it. So, a 5K 120Hz iMac is totally possible. But again, who make the panel? There is almost no 5k monitor now, may be because the display manufacture realise the MST route causing them more trouble than benefit. The 5k monitor exist may be because they made that “mistake” (MST). If no one want to manufacture any 5k 120Hz MST monitor. May be there will be no 5k 120Hz panel for Apple to use.
 
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It's 60 Hz.

Which is fine for its target market.

The iPad Pro running its display at 120 Hz is mostly for the "extra smoothness" when using the Apple Pencil. It looks more natural with the higher refresh rate. The iPad Pro doesn't actually run at 120 Hz all the time, either.

As for flicker - LED backlights should be completely flicker free. It's older fluorescent bulb displays that have a flicker. Here, of my two work monitors, one is an older fluorescent bulb display, the other is a newer LED backlit. Recording a video in slow-motion makes it abundantly obvious:
 
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Just an FYI, the VGAs in iMacs can easily drive 120 Hz at 5k, though only the MacOS UI and maybe web browsing, anything else that taxes the GPU would drop to 60Hz or below.
 
isn't the 27" 5K panel made up (by LG) just for them (Apple) to be able to use retina mode (HIDPI) for 2560x1440 (which is a good resolution for 27") in the first place? :)

There's no use for those LG 5K panels other than 27" retina iMacs, right?
(except LG & DELL standalone monitors)

Remarkable though how Apple followed thru & executed the idea of keeping the 27" resolution (1440p) from the pre-retina iMacs (&Thunderbolt displays) but created better quality by inventing "retina" and therefore getting LG to produce custom hardware just for this purpose.
 
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zerozoneice said:
isn't the 27" 5K panel made up (by LG) just for them (Apple) to be able to use retina mode (HIDPI) for 2560x1440 (which is a good resolution for 27") in the first place? :)

There's no use for those LG 5K panels other than 27" retina iMacs, right?
(except LG & DELL standalone monitors)

Remarkable though how Apple followed thru & executed the idea of keeping the 27" resolution (1440p) from the pre-retina iMacs (&Thunderbolt displays) but created better quality by inventing "retina" and therefore getting LG to produce custom hardware just for this purpose.
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AFAIK, the LG panel itself isn't anything unique. Apple uses their own custom timing controller chip to get the 60Hz @ 5K that DP1.2 can't handle.

Also Apple didn't invent "retina" (other than as a marketing term) - retina is just another word for HiDPI displays. Apple's macOS solution to resolution scaling has some great benefits, but also some tradeoffs compared to Windows way of addressing resolution scaling.
 
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zerozoneice said:
isn't the 27" 5K panel made up (by LG) just for them (Apple) to be able to use retina mode (HIDPI) for 2560x1440 (which is a good resolution for 27") in the first place? :)
Click to expand...

Apple is the largest buyer of LG's 5K panels, but they are also used in the Dell UP2715K and Hp Z27q as well as LG's own 27MD5K.
 
zerozoneice said:
isn't the 27" 5K panel made up (by LG) just for them (Apple) to be able to use retina mode (HIDPI) for 2560x1440 (which is a good resolution for 27") in the first place? :)

There's no use for those LG 5K panels other than 27" retina iMacs, right?
(except LG & DELL standalone monitors)

Remarkable though how Apple followed thru & executed the idea of keeping the 27" resolution (1440p) from the pre-retina iMacs (&Thunderbolt displays) but created better quality by inventing "retina" and therefore getting LG to produce custom hardware just for this purpose.
Click to expand...

And honestly, I have no problem gaming at 1440p on a 5K display. Hell, my Dell 5K displays have a second DP connection that's limited to 4K, and that's what I hook up to my PC. Since it looks fine, and Windows' UI is optimized for 4K anyhow.
 
5k at above 60Hz isn’t possible at this time. Plus the only reason to need more is for gaming (unless you’re doing high frame rate filming) and the iMac Pro was not intended for gaming.

The better question would be why didn’t Apple make a certified HDR 10-bit screen. As far as I can tell the iMac Pro screen is not HDR compliant?
 
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spikerules said:
The best question would be why didn’t Apple make a certified HDR 10-but screen. As far as I can tell the iMac Pro screen is not HDR compliant?
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HDR has only been a thing in PC monitors for the past few months and it's been a bit hap-hazard (Dell's did not fully support HDR10, for example). With VESA publishing their DisplayHDR standards this should hopefully bring some stability. Also, HDR10, Dolby Vision and such were designed primarily for movies, which was not super-relevant to PC displays. Apple instead went with 10-bit Wide Color Gamut support for more relevant media like photography.

LG is now offering HDR displays along with Samsung and Acer and we can expect more down the road. As such, I would not be surprised if Apple adds HDR to the 2018 iMac (Pro) Display.
 
CWallace said:
HDR has only been a thing in PC monitors for the past few months and it's been a bit hap-hazard (Dell's did not fully support HDR10, for example). With VESA publishing their DisplayHDR standards this should hopefully bring some stability. Also, HDR10, Dolby Vision and such were designed primarily for movies, which was not super-relevant to PC displays. Apple instead went with 10-bit Wide Color Gamut support for more relevant media like photography.

LG is now offering HDR displays along with Samsung and Acer and we can expect more down the road. As such, I would not be surprised if Apple adds HDR to the 2018 iMac (Pro) Display.
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Well these iMac Pros are aimed at editors for feature films and TV production, so you’d think it would be the baseline for the Pro? Plus isn’t the display 8bit +FRC panel?
 
theluggage said:
It can be quite hard to find out - http://www.tftcentral.co.uk/ do in-depth reviews on displays which include a test for PWM flicker - and have an in-depth article on it at: http://www.tftcentral.co.uk/articles/pulse_width_modulation.htm#why



Yes - you'll need the appropriate USB-C to DisplayPort or HDMI adapter. Lots of threads here on displays.
Click to expand...

Interesting site and thanks for the additional info on PWM. As I've researched a few other panels, I'm finding that some of them use "constant current" which avoids any flicker. The tough thing is figuring out which ones use PWM and which don't (the information isn't always readily available). Does anyone know whether the current iMac panels use constant current?
 
Hm... I'm a newbie at display tech but I got interested in your responses in this post. The take away seems to be that:

- higher than 60hz, with today's available tech, would require too much battery and gaming-ready gpus
- putting that kind of gpus on macs will make it more expensive and crazy-hungry for battery (macbooks)
- as not many ppl demand that, it wouldn't justify the final price tag for the consumers

Is that it? If so, it would still be nice if by the time the modular Mac Pro comes along apple could offer a Display with native 120hz to please the pro users (not me), huh?
 
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salt5.13 said:
Hm... I'm a newbie at display tech but I got interested in your responses in this post. The take away seems to be that:

- higher than 60hz, with today's available tech, would require too much battery and gaming-ready gpus
- putting that kind of gpus on macs will make it more expensive and crazy-hungry for battery (macbooks)
- as not many ppl demand that, it wouldn't justify the final price tag for the consumers

Is that it? If so, it would still be nice if by the time the modular Mac Pro comes along apple could offer a Display with native 120hz to please the pro users (not me), huh?
Click to expand...
Even 80 Hz would be pleasing. 120 Hz is asking a bit much, as you essentially have to double the bandwidth of the connection to the monitor in order to go from 60 Hz to 120 Hz. Factor in larger resolutions and we start hitting caps on technology.
 
SecuritySteve said:
Even 80 Hz would be pleasing. 120 Hz is asking a bit much, as you essentially have to double the bandwidth of the connection to the monitor in order to go from 60 Hz to 120 Hz. Factor in larger resolutions and we start hitting caps on technology.
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You can get 120hz on a lower-resolution 3rd-party monitor. Just not at 5K. I honestly don't see a use case for Apple building their own.
 
Icy1007 said:
60Hz is fine. Someone might want to see a doctor if they’re getting headaches from using a 60Hz screen.
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60hz is fine.

120hz is better.

Waiting for an iPhone w/ 120hz. That's what I'm hoping to see from this year's phone.
 
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