Windows 10 PC, 32GB memory, GTX 970 GPU
There's more bizarre going on than just the graphics acceleration. I'll try to put together more complete info.
Upgrade to 7.6.3 rendering keeps failing
Re: Upgrade to 7.6.3 rendering keeps failing
Please try Fail safe mode: HF menu->Edit->Preferences->Performance tab: check the Fail safe mode option.
But 4GB GPU may not be sufficient for full-res D850 files.
But 4GB GPU may not be sufficient for full-res D850 files.