I have total of 3 GPUs in my system:
Win 10 64bit with an AMD 7950x CPU with its own internal GPU (on Asus creator x760e wifi MotherBoard) - no monitors connected, an RTX 4060ti as the main GPU with 3 monitors connected, and an RTX 3060ti with no monitors connected.
I have Topaz video AI installed, and to use its multi GPU feature I need to disable the AMD internal GPU, or it slows everything down.
When running Vegas 21, I get a black screen on the preview window.
If I disable GPU preview acceleration - it works fine. but if I wish to enable it, I see only the 4060ti as acceleration option. Not the 3060ti. And when I select the 4060ti - I get the black screen.
If I enable the AMD internal GPU in windows device manager, I have two options to choose from in Vegas 21: AMD and 4060ti. Now they both work, no black screen, but still I cannot see the 3060ti. However, this is not useful as I need the AMD GPU off in device manager for Topaz video AI.
1. Why can't vegas see the 3060ti?
2. Why a black screen with the 4060ti when the AMD GPU is disabled?
I can work for now with the GPU acceleration off, but, really, this is unacceptable. These problems haven't been addressed for years! I had similar issues (different cards, having eventually to turn off the acceleration) for YEARS. Ver 15, Ver 18, and now Ver 21. It's time to address this.
I'm not sure the acceleration works at all, because even with the acceleration turned on, the timeline is not rendered fluently. It can be fine and then suddenly freeze (the audio continues, you can see the dots (.....) appear near the frame number in the preview window and the preview is unusable. I have to stop, let it catch up and continue to play back. With a complex timeline it's impossible to get a reasonable preview.
I have an extremely fast PC, with plenty of GPU power, fast NVME v4 drives (Samsung 990 pro, corsair MP600 pro HN) and the timeline still behaves like 4-5 years ago when I started working with 4K video.