A Demanding Engine That Scales Well
It's no surprise that Far Cry 4 will tax your PC hardware, particularly considering its predecessor. However, if you're not gaming on a high-resolution monitor, you can muster an enjoyable experience from Nvidia's sub-$100 GeForce GT 730 GDDR5 at 720p. Even a lowly Radeon R7 240 provides passable frame rates, if that's all you can afford.
A Radeon R7 250X or GeForce GTX 750 should be considered the minimum for a nice experience at 1080p using low-quality detail settings, and the demands quickly escalate as resolution and fidelity are increased. Medium-detail at 1080p calls for a GeForce GTX 750 or Radeon R7 260X, and ultra detail at the same resolution requires a Radeon R9 285 to keep the minimum frame rate around 30 FPS. Playing at 2560x1440 necessitates Radeon R9 290X- or GeForce GTX 970-class performance. Finally, at 4K with ultra details enabled, only the Radeon R9 290X and GeForce GTX 980 maintain close to the 30 FPS minimum goal.
AMD's dual-GPU Radeon R9 295X2 doesn't yield an advantage over the 290X at this point, hinting that the driver isn't optimized for this game yet. And unfortunately, we couldn't get SLI working with cards from different brands, so we'll have to wait to see how Nvidia's multi-GPU solution pans out. What we can say is that GeForce GTX 980 and Radeon R9 290X owners probably want to step down the detail level if they're driving a 4K monitor to get the smoothest frame rates.
As far as your CPU goes, the Dunia 2 engine scales well with increasing core count. Still, a lowly Core i3-3220 or FX-4170 can push more than 40 FPS minimum at 1080p with the highest details enabled. It's unlikely that you'll see a bottleneck from your platform unless you're running an old dual-core processor that isn't Hyper-Threaded.
For those of you interested in our thoughts on the game, there's not much to say beyond my first-page summary: If you loved playing Far Cry 3, I can pretty much guarantee you will love Far Cry 4. Kyrat offers a wide breadth of enjoyable experiences, despite the deja-vu, in a slicker package than its predecessor.