Fast flickering on Retina iMac

Discussion in 'iMac' started by rainydays, Jan 5, 2015.

  1. rainydays macrumors 6502a

    Nov 6, 2006
    Hi all!

    There is something that I've tried to ignore ever since I got my retina iMac but it's becoming more and more of a problem for me.

    The screen seems to flicker a lot more than the previous generation iMac. Not the "oh my good the screen is dying" kind of flicker. More like a flourecent light flicker.

    I realise that people are more or less sensible to this. I know that I'm unfortunately one of those who are more sensible. But lately I've been thinking that there might even be something wrong with my screen.

    My eyes become very tired after sitting in front of this screen after just a little while. And I kinda wonder if this is how it's supposed to be why no one else seems to be bothered by it.

    Do any of you experience this?
  2. WilliamG macrumors G3

    Mar 29, 2008
    Interesting you bring this up. I think you're dead on about it flickering. I'm pretty sure I was trying to convince myself it's just me, but reading this has me a little more certain it's not just me. I'm not sure there's anything "wrong" with the screen, but more a side-effect of the technology. It's a bummer, that's for sure, and I'd bet we're in the minority even noticing it... I don't notice it all the time, but there are definitely occasions where I'm like omg!

    For what it's worth, I'm ridiculously sensitive to light/flicker etc.

    That said, if you're seeing a really "obvious" (whatever that means..) flicker, then you may have a defective iMac. I'd go check one out at the Apple Store if possible and see if you have the same issue there.
  3. boast macrumors 65816


    Nov 12, 2007
    Phoenix, USA
    I do not experience this.

    But maybe try disabling the automatic brightness control and manually set it to a level which does not flicker for you?
  4. hkoster1 macrumors regular

    Jul 29, 2012
    The Netherlands
    The OP is not saying which GPU he has. It seems to me that most complaints in this forum about the Retina iMac come from people with the "295" GPU, be it about temperature, throttling, and now flickering.

    FWIW, I see no such flickering with my "290" GPU.
  5. redheeler macrumors 604


    Oct 17, 2014
    I assume you are referring to screen flicker, like the kind that CRTs have. I really haven't noticed any difference on my Retina iMac.
  6. ra004e macrumors regular

    Jun 8, 2009
    You might want to check and see if you still see flickering at 100% backlight. Just speculating riMac might be using PWM for backlight dimming, if anyone knows for sure would be worth clarifying.

    Some people have issues with frequency of blacklight when dimmed. A lot of new monitors are PWM free.

    I have base riMac and have not noticed any flicker so far, I keep backlight around 40-60%.
  7. WilliamG macrumors G3

    Mar 29, 2008
    5K iMac is not PWM. Easy way to test, of course, is to point your iPhone camera etc at the screen. You can see the PWM that way. I can see it on my Eizo monitor, but not on 5K iMac.
  8. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    I'm sort of happy to hear that I'm not the only one experiencing this. At the same time I wish that it was something that could be fixed.
    Even though it's not something I'm conscious about 100% of the time I realise that it does affect me negatively.
    Bringing up the ambient light in the room helps somewhat but not completely.

    I wonder if this has to do with the "power saving backlight" of this mac. I'm thinking that they use brighter leds that they have dimmed down. Because dimming led backlights will cause flickering.


    I have the 290, and I don't think that this is GPU related at all.


    Yeah, it's the same at 100% brightness. However, as I said earlier I'm speculating that it might be dimmed even at 100% brightness level.
  9. redheeler macrumors 604


    Oct 17, 2014
    Same, and I've been quite good at spotting minor display problems on mine, having found both backlight bleed and slightly uneven color temperature. Minor issues, but they are there.

    I did test at different brightness settings. It must vary from display to display just like the other issues described.
  10. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    Yeah, i think the uneven color temperature is there on all of them. Even though it sometimes bugs me it's something I can live with. I have slight backlight bleed as well but I know from experience that it could be a lot worse so I can live with that as well.

    Regarding the flickering, from what I understand not all people will be able to see it and it's not something you can train yourself to see. Some are more sensitive than others it seems. So it might be that you have it but just can't see it.
  11. WilliamG macrumors G3

    Mar 29, 2008
    I'd go with that train of thought. There are so, so many issues with so many products that I recognize as issues - and others just don't notice. Sucks to be me, at times. :)
  12. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    Last night when I went to bed my eyes were hurting really bad. And today I've been having major problems with my vision, which I usually don't have.
    I have a very hard time to focus and the eyes are sore.

    Too early to tell if the 5K iMac display is the issue but I'm thinking it might be. Just looking at it now is very uncomfortable. Looking at my MBP screen is much more relaxing.

    I need to find out if this specific iMac has worse problems than the others or if this is by design.
  13. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    I put the previous generation iMac up beside the 5K to compare them. To be honest the older one also has a fair amount of "flicker" but it is less obvious and the screen is much more comfortable for the eyes to look at for some reason. I can't figure out why. It should really be the opposite given how crisp the 5K is.

    I can't find a better word to describe the 5K than "unstable" and perhaps "restless". Where as the older display is stable and calm.

    There is no way that I could describe this to the store I bought it from so that they'd understand and take it seriously. But it is a serious issue to me.
    I can't describe it with any scientific terms and I can't capture it on camera. I guess there is equipment that can measure it, but none that I have access to.

    Another theory might be that the "flickering" is caused by dithering, and that it might switch colors a bit slower since it's such a high res display, thus making it more obvious.
  14. JeffyTheQuik macrumors 68020


    Aug 27, 2014
    Charleston, SC and Everett, WA
    For me, after Day 1, my eyes were tired, and when I woke up, my eyes were puffy and it looked like I was involved in a bar fight (I wasn't, BTW).

    What I noticed was that my glasses (trifocals) weren't ranged in the correct distance, and so I got some at Walgreens (didn't use :apple:Pay).

    Anyway, one other thing I did was get rid of fluorescent lights around my computer. I use an incandescent one, and that, and the glasses, made the difference.
  15. havokslug macrumors newbie

    May 22, 2008
    Change your lights

    I second changing to room lights. LED sources flicker. Your room lights (LED or fluorescent) compounding with the LEDs driving the monitor, making the effect worse.
  16. makdeniss macrumors regular


    Apr 26, 2011
    European Union
    Please install f.lux for monitor temp. and brightness level auto adjustment. Your eyes will be feeling much better. That's an advice coming from a coder.
  17. jordanm86 macrumors regular

    Oct 21, 2011
    I am using a a late 2013 iMac and as my first iMac (I have a macbook pro), I have to say, I am not impressed with the screen and was really hoping the Retina screen would be better quality.

    I am using the third iMac that was sent to me:
    -first one uneven colour - warm at the bottom and issues with third party ram

    -second one, uneven colour - warm in corners and weird smears underneath the top coating of the screen

    - third one (my current machine) slight warming in corners and if I set the brightness to more than 70-80%, severe image retention.

    Personally, I would not buy another combined system again.When this machine comes to the end of it's life, I am buying a Mac Pro and a third party display that is of the quality I would expect.
  18. sth macrumors 6502a

    Aug 9, 2006
    The old world
    This might be a software/firmware problem. I had a very noticable flickering on the iMac 5K screen when I connected my Oculus Rift DK2, which remained even after disconnecting it and rebooting.

    After I did a SMC and PRAM reset, the screen was back to normal (no noticable flicker).
  19. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    Thanks for the replies guys!

    The ambient light makes a little difference to me but not that much. I use halogens as regular incandescent bulbs are being phased out here in Europe.
    Cannot stand LED or fluorescent lights so I don't have many of them in this house.

    I'll consider getting some kind of computer glasses. Feels strange that I would need them for one specific computer since I don't need them for sitting in front of other screens. But I'll book an appointment with a optician soon to discuss that.

    Color temperature or brightness makes little difference for me sadly. That's not what is causing eye the issue for me as far as I understand.

    The flicker/strobing was noticeable the first time I booted this machine up. But I wasn't that bothered by it at first, it has gradually become more and more disturbing. And for the past few days it has become almost unbearable to sit in front of it.
    I can usually sit in front of a computer for days without any eye strain. Didn't have this problem with the previous generation iMac.

    I was hoping that it would be a software issue, but I tried resetting SMC/PRAM and also tried booting up a fresh OS X install. No luck.
    Unless there's a firmware fix for it that is.

    The nearest apple dealer is quite a long way from here so it will take some time before I get to compare it with another 5K iMac.
  20. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    OK, my friend was here and brought her iPhone 6 and we shot a slow motion video of the screen at 100% brightness.

    This clearly shows that it's not just my imagination. And my friend see the flicker/strobing too.

    I finally have something to show to the store I bought it. I'm hoping that it's not like this by design.
  21. WilliamG macrumors G3

    Mar 29, 2008
    I just tried that sitting on my desktop. 240fps slow-mo video from my 6 Plus. I don't see that sort of flickering...
  22. rainydays thread starter macrumors 6502a

    Nov 6, 2006
    Thanks a lot for trying it out! Gives me hope that I will be able to get a screen without this issue.

    I just fear that I will get stuck in a never ending exchange process like I did with my first iMac. Had to replace it six times before I got one that was acceptable (and it still wasn't very good).

    This screen is close to perfect otherwise. But I can't keep a computer that makes my eyes hurt after just a little while.
    I've actually stopped using it now and only use my MBP. My eyes healed after a few days but it doesn't take long in front of the 5K before they start to hurt again.
  23. redheeler macrumors 604


    Oct 17, 2014
    You need to use another 5K iMac for a while, to find out for sure if you have a defective display. It's definitely starting to look that way.

    I took 120 fps slow-mo with my 5s (don't have the 6) and didn't see any flicker either. However, the color temperature differences I've noticed show up clear as day in that video :eek:
  24. sth macrumors 6502a

    Aug 9, 2006
    The old world
    I can confirm that I don't get that kind of flickering on my riMac either (tested with 240fps slomo video), neither on 100% nor on 50% brightness (which is what I use).
  25. Saturnus, Apr 29, 2015
    Last edited: Apr 29, 2015

    Saturnus macrumors newbie

    Sep 14, 2013
    Me too

    I have the problem too. It's been like this since I bought the iMac 5K. I'm quite relieved to finally find people talking about it. I didn't even know what to call it.

    I've tested blue light protectors but it's no better and I was now considering Gunnar glasses for gamers although I concluded that they wouldn't solve the problem either.

    I can't use the iMac - I'm having the same extreme affects: red and sore eyes after as little as 30 seconds of use and after 10 min it's as if I was staring at the sun! unable to focus and the affects stay with me. Looking at other screens after using it continue to strain my eyes. It's pretty extreme.

    The video recorded the affect perfectly. I had been calling it a 'glare' or 'glow' and since most people understand glare as reflection I couldn't find any info - I'm not tech savvy.

    When I have time I'm going to read through the forum again and give a little more information.

    Thank god I'm not the only one!

    I'd like to add that I've tried everything possible. Nothing exterior to the iMac is going to solve the problem and as said before, I'm really worried this is the design and I'm just very very very susceptible :-(

    I´ve just checked my GPU although I don´t understand what it is:

    AMD Radeon R9 M290X

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