You will need a powerful setup to get started developing with UE4 right now. Here’s what we recommend:
Desktop PC or Mac
Windows 7 64-bit or Mac OS X 10.9.2 or later
Quad-core Intel or AMD processor, 2.5 GHz or faster
NVIDIA GeForce 470 GTX or AMD Radeon 6870 HD series card or higher
8 GB RAM
If you have more specific graphics card questions, there may be some answers you can search for here or at forums: https://forums.unrealengine.com/
You can read Tim Sweeney’s thoughts on future requirements here: