Darksiders 2 is running bad. Stuttering :(

Your system seems ok. Probably cause this game is a porting so = optimized like shit.

Try updating your graphics driver

disable background programs and update graphic drivers

I had micro stuttering with Darksiders 2 if being online on Steam. Offline works perfectly. Googled about it and found others who had the same problem. Try playing offline to see if it fixes your stuttering. GTX 670 here.

I heard Darksiders 2 is bad port

I don't see anything obviously wrong with your setup. I just played for an hour for the first time and other than the short intro video (the guy holding the lantern) being a pixelated mess, the game plays perfectly for me at 1920x1200. According to FRAPS my FPS never deviates from a solid 60 with vsync turned on. This game does suffer from a lack of graphics options though. The only thing I saw was a setting for antialiasing. It seems that most people having framerate or microstutter problems (and with Saints Row 3 as well) are running nvidia cards with Intel chipsets. That could be because more people happen to use nvidia and Intel together than straight AMD setups, so I don't know if that is enough to draw any clear conclusions from.

Phenom II X4 BE @3.4GHz - 16GB DDR3 - HD7870 - Gigabyte GA-990FXA-UD3 (AM3+)

It's not ur pc, just lazy devs fault who ported the game and couldn't be arsed to fix the issues, sadly i don't think they will ever patch it.

Try to disable v-sync in-game and enabling it on the nVidia control panel. It worked for me.