Far Cry 4
Far Cry 4
System specs are usually vague and lack clear details. As mentioned before, if you can handle Far Cry 3, Far Cry 4 should be comparable, possibly a bit more demanding. The best approach would be to wait until official benchmarks are released, though I think it should still work fine.
BF4 offers better performance and better support for AMD hardware compared to FC3. FC4 adds more demanding features such as PCSS. With my 7950 graphics card, I maintain over 40fps in BF4 while running all visual effects, @1440, ultra settings, and 2X MSAA. If you have an AMD GPU with the FX 4100, I wouldn't recommend purchasing FC4—it's not a good value. There might be some solutions to get through, but they probably won't make it worthwhile. This is exactly what I experienced in FC3 with all its optimizations, patches, and updated drivers: ultra and maximum settings.
Your setup is suitable for medium and high settings on your Radeon 7850 with 8GB RAM. You likely won’t hit the limits for FC3, and performance should match or exceed FC4.
Did you play fc3 at around 30 frames per second? 1440p isn't necessary.
If they removed shadows and plants at that height, it might be under 40, which isn't too bad.