Rendering glitches when dGPU NVIDIA GeForce GT 750M active in specific apps Photos and Safari
Number:rdar://FB9001334 Date Originated:2021-02-11
Status:Open Resolved:
Product:Graphics Product Version:macOS 11.2.1
Classification:Incorrect/Unexpected Behavior Reproducible:Yes
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In the recent weeks I experience graphical glitches in specific apps only (Photos + Safari)
on my MacBook Pro (Mid 2014) and only when running on its dGPU which is a NVIDIA GeForce GT 750M.

For a number of reasons (see inline) I do not think that this is thermal, aging issue,
but rather a software issue having to do with recent updates:
NVIDIA driver, MetalAPI, possibly recent Firmware/BootROM upgrade.
Glitch I in and Glitch II in Safari are both 100% reproducible!

- Roman numerals refer to the separate observed glitches.
- Arabic numerals refer to the provided screenshots / screen recordings.


Always correct behavior on iGPU (100% reproducible)​

- Disconnect power adapter to run on battery
- Launch, it runs on the iGPU
- Switch from "Months" to "Days" view and later back again
- Perfect animation, always

Always faulty behavior on dGPU (100% reproducible)​

- Connect power adapter

- Launch, it enforces dGPU
- 1a) Switch from "Months" to "Days" view and back again
-- During the transition within the content canvas of the single-window-app:
--- The upper ca. 30% and lower ca. 30% off the canvas show the faulty behavior:
--- Random white/grey lines, triangles or rects overlaying some of the photos.
-- Sometimes this does not happen at the first transition, but just scroll up or down a bit, and then transist, and latest at the 3rd-5th repetition you get the glitch.
--- And if you then transist back and forth, without scrolling inbetween, you always reproduce the glitch

- 1b) If you are already in the bug and then scroll within the "Months" view, then the gap surfaces between the photos flashes in full white or with white zig-zag lines.

GLITCH II in Safari​

Not reproducible. But when occurring certain environment commonalities are observable:
- Experienced this twice within 8 days while using my computer ca. 6 days a week for 6-10 hours a day.
- Both times happened on, though on different project pages.
-- Not on other domains, and I sure visit 100 different domains/websites per day.
- Always occurred while on dGPU:
-- On 2020-02-03 I ran on an external display which enforced the dGPU.
-- On 2020-02-11 I ran on the internal display, had running in the background (I explicitly mean the GUI, not the daemons like photoanalysisd), which enforced dGPU.

2) Visible glitches​
- Black squares and triangles (assumingely polygons of accelerated graphics)
- Font rendering shows broken glyphs

3) Workaround:​
- 3a) When Safari suffers the glitch
- 3b) Switch from dGPU to iGPU
-- I did this while running on power adapter effectively by quitting the only dGPU dependent app
- 3c) Thermals were unsuspicious while that time. Fans very relaxed.
- 4) Also other people on the Internet report the same symptoms​
All of late 2020 or early 2021, so very likely all related to recent Safari and macOS Catalina / Big Sur. And in many cases mentioning NVIDIA GPUs.

4a) Weird black triangular graphics disruption

4b) Safari graphics glitch with MacRumors

4c) Safari graphics glitch with MacRumors nr2

GLITCH III in Safari​

Always reproducible!
- 5a) I now have a stable reproduction:
-- With your external display connected, hence the dGPU on, open Safari
-- Open (a weather website)
-- The satellite/weather image sequence shows a rendering glitch: Green rectangles (ca 90x50px) along a diagonal axis are shown above that satellite/weather image sequence. Regardless where the playback/slider is.
-- 4d) exactly as user @Benblob688 reported on
-- 5b) For comparison, while still on dGPU the same website renders flawlessly on Brave Browser (Chromium web engine)
-- In Safari: As soon as you switch to iGPU by disconnecting the external display, the window re-renders instantly, and all is fine!


- These were the things which I recently changed:
-- 2021-01-18 Upgraded macOS 10.15.7 with 2020-001 Supplemental (had postponed this for long)
--- macOS: 10.15.7 19H15 -> 19H114
--- Boot-ROM: -> 429.
-- 2021-01-21 Upgraded macOS 10.15.7 Catalina to 10.11.1 Big Sur

Glitch II in Safari definitely only experienced first on 2020-02-03. Never before.

Glitch I in Photos I only deliberately noticed on 2021-01-29 in Big Sur and thereafter.
- But I may have already noticed it in Catalina somewhen 2020 and ignored it, rarely used it then.
- Luckily I still had bootable backups of Catalina and Mojave and booted them on the same machine with the meanwhile newer BootROM 429.0.0.0 and ran:
-- Photos in Catalina: Exactly the same glitch happens!
-- Photos in Mojave: Different navigation paradigm "Photos | Moments | Collections | Years". But I scrolled around wildly and zoomed in and out wildly, and no glitches at all!


- My thermals are overally very ok. The fans are mostly silent, also when the incidents happened.
- I never have rendering artefacts on the screen in general or in other apps.
-- Only in the forementioned specific apps Photos and Safari.
- Other 3D apps work without glitches:
-- Apple Maps in 3D mode in cities which have the 3D buildings
-- Brave Browser running Google Maps in 3D mode
-- Google Earth Pro (seems to use Qt/OpenGL)
- I don't think (or hope) that it's first signs of dGPU death as it was on my MacBook Pro (Late 2006) with the widely spread contact-pin issues of this series back then. The difference there was that heat indeed noticable and the glitches were general and not app-specific.
- So I assume it's indeed a software issue (NVIDIA drivers, Metal API, maybe recent BootROM upgrade v162 -> v429) and hope that it will be solved.


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