That’s a positive! Like I mentioned to ADGrant can you also please post a comment if you do see the white line again as I’m sure we’d all be interested to know if installing the updates after the initial setup has resolved the issue.
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iMac 2020, 5700XT - graphical glitch?
- Thread starter torifile
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That’s a positive! Like I mentioned to ADGrant can you also please post a comment if you do see the white line again as I’m sure we’d all be interested to know if installing the updates after the initial setup has resolved the issue.
Thanks for that explanation.
If you change the option to the "More Space" setting, then what does the "Looks Like" resolution then change to?
I feel like I should say, for those that are watching this thread, that for me this is a super minor thing. I have barely noticed the problem at all. I'm more curious than anything, but I'm certainly not returning it or anything, and generally really happy with this iMac. I'm not making excuses for an expensive machine, but seriously, for me, its not a big deal. And to be clear I understand and respect other's opinions on this. I would bet based on my experience with Apple that this will be fixed in a software update.
I agree that different people perceive things differently. What one person deems "excessive fan noise", but be considered acceptable to some.
From someone who hasn't yet purchased, my gut feeling is that if I was editing photos, and was frequently hit with this flashing white line, it would be a major problem to me. I am quite picky though.
I feel like I’m also picky, it’s just that this white line has maybe happened 20 times total in 2 weeks.
All the way to to the right on "More Space" says "looks like 3200 x 1800"
The five options are
1600x900 - scaled 3.2x
2048x1152 - scaled 2.5x
2560x1440 - scaled 2x (default)
2880x1620 - scaled 1.78x
3200x1800 - scaled 1.6x
None of them scale 1:1, if that is what you are wondering
Retina, or HiDPI, or "Looks like" modes draw all text and objects at twice the height and width of "low resolution" modes (four times larger).
You can see low resolution modes (such as 5120x2880) by holding the option key and clicking "Scaled". Low resolution modes draw text and objects like Macs did before retina existed (regular hight and width).
Objects are drawn into a frame buffer (nvram of the GPU) with a certain resolution (for example, 3200x1800 for "Looks like 1600x900").
The frame buffer resolution might be lower (3200x1800) or greater (6400x3600) than the resolution of the display (5120x2880 for 5K display).
This frame buffer is then scaled by the GPU to produce the output resolution/timing which must fit in the bandwidth of the connection. Usually the output timing matches the resolution of the display (5120x2880).
However, you can create timings (non-scaled resolutions) that differ from the resolution of the display. The display has its own scaler to scale the output timing to the resolution of the display. Some displays can accept resolutions that are higher than their native resolution. For example, my 4K display can accept a 5K60 or 6K48 or 8K30 timing as well as the usual lower resolution timings 480p, 720p, 1080p, 1440p etc.
For each timing (low resolution mode), a HiDPI mode also exists using the same timing ("Looks like" half the width and height). For example, the 8K30 timing I created gets a 8K30 low resolution mode and a "Looks like 3840x2160" HiDPI mode.
For every scaled resolution, two modes are created for all the timings for a base resolution (usually the resolution of the display) a lower resolution mode and a HiDPI mode. By default, the base resolution is usually the same as the resolution of the display. For my 4K display, the base resolution is 4K which has timings for 30Hz, 50Hz, 60Hz, 95Hz, 120Hz. So a 6400x3600 scaled resolution would have 5 low resolution timings, plus 5 HiDPI timings.
macOS does not have a method in the UI to show the current output timing. You cannot know that a 5K framebuffer resolution is being scaled to 4K output timing by the GPU (as happens when a LG UltraFine 5K display is connected with USB-C instead of Thunderbolt) unless you view the timing info using an app like SwitchResX or looking at the output of a command like AGDCDiagnose. In the case of the LG UltraFine 5K or iMac 5K display, the 5K timing info is actually faked to appear as a single 5K timing instead of two 2560x2880 timings - but at least you'll know it's 5K total instead of 4K. The AGDCDiagnose will show the connections and original non-faked and non-overriden EDIDs (one for each half of the display).
macOS does not have a method in the UI to show the current output pixel format. It shows the frame buffer pixel format (e.g. ARGB2101010) but the output pixel format could be RGB 8bpc or YCbCr wth or without chroma sub sampling. Chroma sub sampling happens with my Mac mini connected to my 4K display with HDMI. Chroma sub sampling throws aways some color information. RGB 8 bpc produces a better image - especially for colored text.
macOS does not have a method to change output pixel format. You can use SwitchResX to change the framebuffer pixel format (between millions of colors = 8 bpc, and billions of colors = 10 bpc). To change from YCbCr 4:2:0 (chroma sub sampling) to RGB 8 bpc you have to override the EDID to remove the chroma subsampling option. Recently, Apple added a HDR option to the Displays preferences panel. This does change pixel format (enables HDR color and forces 10 bpc) - so maybe there's a hidden API that someone could use to change output pixel format.
macOS does not support 6 bpc. Windows Nvidia drivers have that option. It's fewer colors - but macOS can do dithering to handle that so you don't get banding when looking at a gradient. I've seen banding appear and disappear even when using 8 bpc or 10 bpc. It's kind of weird because an app might show banding one moment but not another moment. If there's no banding, it's difficult to know if that's because 10 bpc is being used or if dithering is being used. Some apps might draw using 8 bpc even if the framebuffer pixel format, output signal, and display are all set to 10 bpc.
macOS does not support MST hubs for multiple displays. Windows does. DisplayPort 1.4 MST hubs are more powerful than their older DisplayPort 1.2 hubs because they support DSC (Display Stream Compression) to allow more higher resolution displays that would normally exceed the bandwidth of a single non-DSC DisplayPort connection (the hub can convert DisplayPort signals - link rate and number of lanes - and can decompress DSC for older displays). Many USB-C hubs and some recent Thunderbolt 3 docks use an MST hub that is not utilized by macOS.
One thing macOS can do that Windows can't (I think?) is support 6K over Thunderbolt for non-DSC GPUs. Windows can do 6K using a GPU that supports DSC.
Honestly, it’s more a disappointment, than of an annoyance. But when you spend thousands $$$ on a new computer, it shouldn’t have an issue out of the box. I ordered two identical iMacs. Both had the horizontal line issues. I kept one and returned one. Apple seems to be taking this issue seriously and I agree, this seems like a software issue. But the reality is a fix may not come for a long time. Safe thing to do is buy the 5700 instead of the 5700XT. If you can wait, I would hold off for a month and see what happens. Maybe we are the 50 people or so with issues out of the 10,000 that shipped? I see some people posting that they don’t have issues, but maybe they just haven’t noticed because the the glitch happens so infrequently and randomly.
QUESTION: If this was a software glitch and we are all on the same software and we are all using the same iMac, wouldn’t that mean it has to happen to everyone with the 5700XT?
I am not sure if buying the 700 instead of the 5700XT is the safe thing to do but personally I wouldn't change my purchasing plans over such a minor glitch. All computer software has issues including the software in modern cars. Buyers of $80,000 SUVs have experienced far more significant software issues than these.
Like the previous poster, I think people may be over reacting here.
Actually after returning the i7/5700XT and receiving a new i7/5700 model, the white line problems goes away, but the flickering/square window corners does not.
I wonder how Steve Jobs would have reacted. Since his death the iron hand is gone. I’m a user for over 30 years, had the whole line of iMacs and never had any problem, so it is also a matter of pride and it hurts to see that it came so far. So overreacting , maybe, but in some way it does’t feel right.
Have you noticed if the 5700 is running cooler than the XT? In theory it should ... but in reality?
I suspect so, but considering how quick the flashing white line is, who is to say the people claiming not to have it, haven’t just missed it? Blink, and you could miss it.
its a bit like the coil whine issue with laptops. Some users insist their machines don’t do it, but are they placing their ear against the keyboard in a dead silent room like I am? Probably not.
Not really. Everyones usage patterns and workloads are different. Defects that manifest themselves infrequently can be easily missed.
For example, I rarely drag my Mail window around on the screen, in fact I don't drag apps around the screen very much at all. I use the spaces feature in mission control to arrange my windows and then I swipe between the spaces with my trackpad or CMD Tab between apps. I would never have noticed the corners on the mail app if the issue had not been raised in this thread.
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I’m not sure the flickering corner and the white line is related. I have the flickering corner on mail, sometimes on finder and not (yet) on safari. On mail its constant there. On finder it’s for the first 5 s of moving the window around. Then it’s gone. I think I can live with that - you have to look for it to see it.
Haven’t had any white stripes yet. That I would not be able to live with on a >2000$ brand new computer.
I have the 5700XT, 8 core i7, assembled in Ireland
Haven’t had any white stripes yet. That I would not be able to live with on a >2000$ brand new computer.
I have the 5700XT, 8 core i7, assembled in Ireland
People have lived with far bigger problems on a >2000$ brand new computer.
Exhibit A: The butterfly keyboard.
I decided to go with the 5700XT and slapped on AppleCare+ (cheap 3yr insurance)... I'm quite confident Apple will fix this issue one way or the other. Can’t keep delaying the purchase or else the new iMac will become an old iMac, haha!
For the past 2 weeks I've considered 5700 -> 5700XT -> 5500XT -> 5700 -> 5700XT.
For the past 2 weeks I've considered 5700 -> 5700XT -> 5500XT -> 5700 -> 5700XT.
Sure. I’m not saying this I worse. But if Apple (still) wants to make the best computers they should address such issues.
I would not argue with that but I think perhaps we are getting a bit over excited by this issue on this thread.
I have bought 2020 i7 8 core iMac with 5700. I’ve been having issues since day one. Stuttering when resizing windows.
When playing any of my games from the app store the sound is acting up with popping noises at regular intervals. The more graphics demanding the game is the more the sound is messed up. I just finished talking with the apple care rep and I may have to return the iMac since there may be no easy fix for these issues.
Unfortunately I have already bought 64 Gb’s of RAM.
Maybe yours is a lemon. Can they ship you out a new one to see if it fixes the issues you're experiencing?
I have the 2020 i7 with the 5700 and have been having issues from day one. None of my App Store games play without a glitch.
There are popping noises at regular intervals when playing games. The more graphics performance the game requires the more the sound acts up. I am going to test it with some 4K editing in a few days. I also noticed stuttering when resizing windows. With no easy fix in sight Should I return this iMac? I need some useful advice.