Hi Rozhok,
I’m not sure if that GPU will run the editor fine or not. The short answer for why a game may work but the editor may not is because the editor has to do a lot more work.
The longer explanation is the games are cooked, lighting is baked, and optimized and configured not to do anything but run the game. The editor has to run un-optimized, nothing is cooked or baked because everything is changeable. It has to keep a lot more assets in memory than a normal game would, and it has to render all of the tools UI which we also run on the GPU.
Cheers,
Nick (Epic Games)