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Text rendering worse on eGPU?  

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Alex Ray Dotte
(@alex_ray_dotte)
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Joined: 2 years ago
 

Has anyone else with a 4k monitor noticed that text in some applications tends to look different when the display is connected to an eGPU and a Thunderbolt 3 MBP vs the internal graphics?

In most apps it's not really noticeable, but when I'm running Visual Studio Code and my favorite color theme (Kimbie Dark) on a Dell P2415Q 4k monitor, the red text in particular is noticeably 'pinkish' and blurry than when connected directly to the MBP's internal graphics. It's bad enough that I usually prefer coding connected to the internal graphics.  Unfortunately the MBP chassis runs noticeably warmer and I lose hardware acceleration for other apps when doing this, so it's not ideal..

I'm using a 2018 13" MBP and an RX 580 with the Breakaway Box, btw. Also have a 32" BenQ 2560x1440 monitor connected to the eGPU that doesn't have this problem.

To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.

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Alex Ray Dotte
(@alex_ray_dotte)
New Member
Joined: 2 years ago
 

Update: Installing Mojave fixed it.

Dark mode FTW 😎

To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.

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charles_cactus
(@charles_cactus)
New Member
Joined: 2 years ago
 

Even though you already fixed this issue I just wanted to post my own findings that might be useful to someone else. 

In High Sierra I noticed color fringing around text when using an RX 580. It was so bad in Xcode that I considered it unusable, it was worse with a light on dark theme but even with a white background theme (gross) it was still unusably bad. I ended up returning my 580 and upgrading to a Vega 56 for game performance reasons and found that it actually fixed the color fringing issue. So apparently text rendering quality can actually vary from card to card.

To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.

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MacBowtie
(@macbowtie)
Eminent Member
Joined: 1 year ago
 

Reviving an old thread.

Yes, I have the same problem. MacMini, Mojave, AMD580/Aktio Node Pro.
At 2560px resolution, text looks really weird. Some kind of mixture between "pixelated" and "slightly blurred". In all apps: web browsers, Photoshop, Finder. Everything.
I also get the impression that the palette icons in Photoshop look pixelated/blurry. Though I may be staring at the screen too much, now that I've noticed text looking weird. Will need to compare when I switch to the internal graphics again.

No colour fringing, though. But bad enough.

2018 MacMini i7 / Mac OS Mojave / 4k iiyama screen


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MacBowtie
(@macbowtie)
Eminent Member
Joined: 1 year ago
 

Update after taking a closer look, comparing eGPU with internal Intel graphics (2560px resolution)

Indeed, it's not just text that looks pixelated, but also everything else like palettes in PowerPoint / Photoshop / Illustrator etc...

Is this a driver issue? Or an issue with my GPU (XFX AMD 580)?

2018 MacMini i7 / Mac OS Mojave / 4k iiyama screen


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mac_editor
(@mac_editor)
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Joined: 4 years ago

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MacBowtie
(@macbowtie)
Eminent Member
Joined: 1 year ago
 

@mac_editor

Unfortunately not – doesn't make any difference at all. Anyway – it's not just text that's affected.
I think it may even affect pictures. Will take a macro-shot with my DSLR from a tripod, for comparison, as soon as I get the time.

2018 MacMini i7 / Mac OS Mojave / 4k iiyama screen


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MacBowtie
(@macbowtie)
Eminent Member
Joined: 1 year ago
 

@mac_editor

Did a macro screenphoto today, to illustrate the difference between internal and eGPU. Shot with a 100mm macro lens on a Canon 5DSR. Not perfectly aligned (hence the moirée). Photoshop zoom level is 100%.

MacMini internal graphics:
https://imgur.com/wRGP5IK

eGPU:
https://imgur.com/4R99ubF

Screen settings:
https://imgur.com/aUz2WXc

This is from inside Photoshop. All text layers are rasterized. The black lines are from 1px to 10px apart, and exactly 1px wide. On the AMD 580, some of the vertical lines go missing completely – which is what annoys me more than anything else. This is a complete no go for retouching!
White-to-black gradient is smooth, though. No banding.

Independent of the graphic card: what's really weird is: the document is 2560px wide, the system preferences say "looks like 2540 x1440", yet at 100% zoom level in Photoshop, the document only uses up half the screen's width...
I'd like to add: I'm not new to Photoshop, but this is my first step into the eGPU/4k-screen world. My old screen was 1920px wide, and a 1920px wide document would fill the exact width of the screen.

Could it be that the card is faulty? I bought is used of eBay (from a commercial seller who had about 30 of these cards going). Checked with XFX, and the serial number shows an original purchase date of 2017, from Lithuania. I've read reports about bad cards that had been used for mining. But I'd like to think a card either works or it doesn't. (On the long run, I'll probably upgrade to a AMD5600 anyway, as soon as the drivers are ready).

2018 MacMini i7 / Mac OS Mojave / 4k iiyama screen


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mac_editor
(@mac_editor)
Famed Member Moderator
Joined: 4 years ago
 

@macbowtie

Quickly saw this on the phone and it’s as you say - looks horrid on eGPU.

purge-wranglertbt-flashpurge-nvdaset-eGPU
Insights Into macOS Video Editing Performance

Master Threads:
2014 15-inch MacBook Pro 750M
2018 15-inch MacBook Pro

 
2019 13" MacBook Pro [8th,4C,U] + RX Vega 64 @ 32Gbps-TB3 (Mantiz Venus) + macOS 10.14.6 & Win10 [build link]  


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rnb2
 rnb2
(@rnb2)
Eminent Member
Joined: 2 years ago
 

@macbowtie

I can answer one part of your question - the less important part, unfortunately. The key here is that you're running a 4k screen at a resolution that "looks like 2560x1440", so you're not actually running at that resolution, because your 4k monitor can't (it's 3840x2160 pixels, no matter what). When you set your resolution at anything greater than the default (or ½ the actual pixels - the 1920x1080 setting), what macOS does internally is render off-screen at 2x your "looks like" resolution - so 5120x2880 in this case - then simulates the result on your 4k screen. This is why your 2560 pixel document only takes up ½ the screen - graphics/photos/video are rendered in actual pixels, only interface elements are rendered at 2x. So, your 2560 pixel document is rendered off-screen at 2560 pixels wide on a 5120 pixel wide virtual screen, then everything is mapped down to the 3840x2160 pixels of your display.

I'm afraid I don't know why everything looks so awful via the eGPU, though. Haven't experienced that myself, and I'm running Catalina now, so can't test.

This post was modified 8 months ago

2018 i7 Mac mini - OWC Mercury Helios FX (Sonnet 550) - ASRock Vega 56 - BenQ SW271


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