weird 17.4.1 eGPU bug makes it unusable

Greetings,

Wondering if anyone can help with this problem I've had ever since 17.4, in that playback is so badly stuttering it's unusable, on all media, whether cached, or rendered in place. As soon as I uninstall and revert back to 17.3.2, it goes away and playback is just fine, so that indicates to me it's a bug in 17.4.1.

It's apparently related to my eGPU setup. I've got the last intel MPB with the fast 5600M GPU internally and a Vega Frontier in the eGPU box, OS is Catalina. All plays fine (mostly C300 Mark II 4K footage, but with all other media as well) when using 14.3.2 (I've confirmed this several times with uninstalling/reinstalling the two versions to hunt down the bug) and it certainly only happens using 17.4.1 with the eGPU.

Here's where it gets even more weird. I run three monitors off the eGPU, set up above my MBP and its monitor for a total of four monitors in use. With 17.4.1 it always stutters, with or without video clean feed, on one of the eGPU monitors. However, I pulled the UI down to the MPB monitor (both GPUs are checked on in prefs, using Metal, btw) and the playback is much better, but still a bit stuttering. Video Clean feed is also better but stutters worse than the MBP monitor. The weird thing is, I could not find a way to get the UI back up into any of the eGPU monitors. It just wouldn't accept being moved into them, like the Resolve UI refused to recognize their existence (at the same time, all other windows had no problem moving around in the arrangement). So I once again reinstalled 17.3.2 and now it's all good again in both playback and being able to move the UI around between eGPU and MBP monitors.

I really like 17.4.1 and would love to use it but I simply can't as it is now. Any suggestions anyone? Thanks in advance.

So I'm not active on any project right now so I took the plunge and upgraded the OS to Monterey. Booted up Resolve 17.3.2 and it told me the software needs to be updated for Monterey. So I installed 17.4.1 and the problems have not changed at all. Still unusable playback.

I forgot to mention that the renders in 422HQ or .H264 of the same timelines that stutter play back very smoothly on the eGPU screens, which is strange because all of my clips in the Resolve timeline are cached as 422HQ.

Would love any thoughts...

[Dwaine Maggart]

In a multi-GPU scenario, all displays must be on a single GPU.

Since you MBP display is on the internal Intel iGPU, you can't put displays on the eGPU without impacting Resolve performance.

As a test, remove all the eGPU displays, and I suspect you'll see much better performance.

Also, in Finder, go to the Applications folder, then the DaVinci Resolve folder, and right click DaVinci Resolve.app and select Get Info. In the Get Info window, make sure Prefer External GPU is NOT checked. This is the opposite of what was recommended prior to Big Sur. I assume on your system, it's already not checked, or Resolve probably would not launch.

Thanks Dwayne,

I'm rather dependent on my eGPU monitors, though, particularly my Eizo on the eGPU for clean feed colour correction. I really can't do everything on my Macbook Pro monitor, and my overriding point point of interest is that it works just fine under 17.3.2 but not in 17.4. I just tried 17.4.2 and it didn't work either, in Metal or OpenCL (where the UI wouldn't even give me any image on either the UI or clean feed, just a blank screen). Uninstalled 17.4.2, then reinstalled 17.3.2, and everything is fine, using an eGPU.

I really hope Resole isn't abandoning eGPU support. That would be a big problem, potentially driving me off the platform. I need smooth playback and don't understand why it was fine on an earlier version but not possible now.

[quote="Dwaine Maggart"]In a multi-GPU scenario, all displays must be on a single GPU.

Since you MBP display is on the internal Intel iGPU, you can't put displays on the eGPU without impacting Resolve performance.

I forgot to add that previously I only had the eGPU selected, and manually unselected the iGPU so that the workload would be distributed between the internal CPU and external GPU. I'd run resolve only on the three monitors coming out of the eGPU and they worked fine like that. Until 17.4 and now it doesn't work at all.

Posting again to report that it appears I didn't have "prefer external GPU" checked in the information window of the the Resolve app. It didn't/doesn't appear to matter with the earlier versions of Resolve, at least it didn't with my platform and on different OS's, but it appears to matter now. Thanks for reminding me of that. Playback is smooth on my external eGPU monitors now in 17.4.2.

I think is the optimization for M1 computers.
Mine too is unusable, the performance drop heavily.

M1 Computers don't support eGPUs.

Maybe I didn't explain myself:
having done an optimization for M1,
we were left out as we used an eGpu.
Same thing that happened with Final Cut:
suddenly, the same computer with the same eGpu started to run very slow, without warning.
It would have been fair to warn users that some configurations would run slower.

M1 Computers don't support eGPUs.

If you close the lid on the MBP and only use the external egpu driven displays.
Do you see the performance picking up again or is it still laggy?

17.4.2 build 9, trashcan with eGPU. Playback and render tops at ~18 fps no matter what the source and project settings. With eGPU disabled in preferences, it's back to normal.

I've been on this system for almost two years and eGPU was actually a considerable performance boost.