No one has a clue about this? GPU accelerated rendering is really skipping some plug-ins and/or sequences. (even when not using other specific softwares). (Wasting hours of encoding here ...)

I use an AMD GPU and aside from two or three plugin not working with it, some I have only used once in many years, I have no issue with GPU acceleration. But, I am also still on Sony Vegas Pro 13 for that reason.

Have you tried different driver versions for you GPU. I do remember seeing a lot of post with issues specifically related to GTX9xx models.

I have requested over the years that Vegas should have a compatibility test tab. This would be under preferences, or Help > Compatability. This small program would check things on the system like .NET, OpenCL, Integer and FP performance, Memory bandwidth, disk performance, and now the NVENC, Quicksync functions.

If Vegas is going to bundle other 3rd party plug-ins, then the compatibility tester should verify the timeline and render functions against the supported codecs. Then list this in a grid form.

This all might seem terribly diagnostic and overly technical given a creative software. But people are just stabbing in the dark with system configurations, and they buy the cheapest hardware they can get a away with. A diagnostic tester would rule out cheap/gimped hardware from the support issue.

The 980 may have been a good card back in the day, but Vegas 15 is leaning on contemporary hardware features more and more. The diagnostic app would tell you if your hardware was now obsolete.

There are 2 different areas to consider with the NV980:

1. Timeline GPU acceleration is dependent on OpenCL, and now with VP15 there could be a certain amount of NVENC decode. NV cards of generations past did not perform well with OpenCL, hence the recommendation of using AMD for better support.
2. Rendering GPU acceleration does a small amount of OpenCL math, but with VP 15, the onboard ASIC (NVENC & Quicksync) are being used to perform the H264 compression much faster than CPU*. The * in that statement mean there is a trade off in quality for the speed.

You really need both supported for the best Vegas experience, and you need a configuration that works stable in these modes more than anything. People often blame software for hardware problems. Vegas works hardware buses and components much harder than a game, or browser operation.

@astar: Thank you for the comment.

Yes, I'd like Vegas to has some diagnostic tool too...

I think I didn't mention yet that my "non-deterministic render" problems also happen when encoding uncompressed AVI. First I though uncompressed AVI was not affected by GPU acceleration (I though "that" GPU acceleration setting was only for previewing actually). But appareantly it does.

Yet I have already encoded the current project I'm working on multiple times in both AVI and H264 (1080p and 2160p) ... it's just that I corrected pan/crop keyframes and want to reencode, but now I can't get the 4K version fully encoding any way I try. Not sure what has changed since then.
(I'll still trying to encode with GPU acceleration off tonight, which tis estimated to approximately 3 hours.)

@OldSmoke : Yet, I tried various version of NVidia drivers, including the latest version today. But I can't see any correlation between drivers changes and things disappearing/re-appearing in Vegas.

After some more test without GPU, I'm thinking the apparently non-solvable problem I'm encountering with my current project may not have to do with GPU. Trying to re-render the previous version of the project to see if it works better. Otherwise I can try re-installing Vegas, if this doesn't work I'm completely lost regarding this issue.

I have requested over the years that Vegas should have a compatibility test tab. This would be under preferences, or Help > Compatability. This small program would check things on the system like .NET, OpenCL, Integer and FP performance, Memory bandwidth, disk performance, and now the NVENC, Quicksync functions.

If Vegas is going to bundle other 3rd party plug-ins, then the compatibility tester should verify the timeline and render functions against the supported codecs. Then list this in a grid form....

Great idea! 👍

I also think they need to add one more feature to that diagnostic setup you suggested... Neat video, my favorite noise reduction plugin, will run tests on your system. It will do single core no GPU all the way to all cores, then run the same test again with GPU enabled, and pick out the combination that resulted in the best performance (in my case, it was using all but one CPU core (7 cores) with GPU assisting). Vegas needs something like this to auto-calibrate the dynamic RAM preview amount recommended, max rendering threads, encode mode used, etc. so we can tune our systems to get the most performance out of Vegas. I understand that each project's needs are different, so maybe there could be a way to run that optimizer on any project you want to determine the best settings... For instance, Neat Video uses some of my GPU ram. when I had it set to use all of it, and tried to do an NVEncode with Vegas, it would freeze. I had to reduce the GPU ram usage in NV to like 40-50% to get vegas running smoothly. It would be nice to be able to scan a project to see what the various needs of the effects and plugins used are, and balance the system accordingly.

I'd rather features like this and bug fixes over any upgrade to the program. Get that foundation poured and rock solid, then build on it.

At least one good news, but it's only about my current project:
In addition to the wrong encoding I observed used GPU acceleration and some plug-ins on various projects. I found the way through this one that couldn't get encoded. Version 8 was always missing some sequences, version 7 was encoding right. I copied version 7 to version 8b. I copied the few changed pan/crop key frame from version 8 to version 8b ... I had to do it at least three times to get Vegas to save version 8b without crashing. Version 8b is now encoding fine. I guess my project file was corrupted, which only added confusion to the GPU acceleration complications.