I just built myself I killer new rig. It is by no means the most powerful system in the world but compared to the computer it replaced the difference is night and day. I have tried many new AAA titles looking for something to bring it to its knees and so far haven't found much that the rig can't handle. I thought Far Cry 3 would to do but no. While it looks amazing, it runs like butter. I have heard Metro 2033 is a beast but it is 2 years old and I find it hard to believe a game that old could tax modern hardware.
Even Planetside 2 plays smooth save the few times there are 200 players attacking/defending one base. DayZ looks freaking awesome with max details but still runs like butter.
What game do you all think is the most taxing on modern hardware?