Yes 3GB is enough. But what GPU are you using? It will depend on the GPU.
Oh I forgot about it
it's Sapphire R9 280X Vapor-X.
For 1440P, your card can run Battlefield 3, TES V:Skyrim with High to ultra settings @ 40-60 FPS without any problems.
Battlefield 4 will run in this card at 1440P with an average of 50-60 FPS.