Unreal Engine 4 won't run on current hardware... except for Nvidia's Kepler, that is.
Unreal Engine 4 Not For Current Platforms (Except Kepler) : Read more
Unreal Engine 4 Not For Current Platforms (Except Kepler) : Read more
Getting back to Unreal Engine 4, Epic hopes to showcase the new platform in public by the end of 2012. It's also reportedly running on a single card powered by Nvidia's Kepler hardware. Last year the Unreal Engine 3-based "Samaritan" demo required three high-end Nvidia cards and a monster PSU -- now it runs on the same single Kepler-based board used by the UE4 demos.
"We can get so more out of that card than what you saw in Samaritan," said Epic Games VP Rein during GDC. Sounds like hardware is finally catching up with the software.