Here's the screen shot http://i.imgur.com/YOIlwyO.jpg
Iv'e googled this issue and it's apparently related to Physx, it can be removed by eather playing on a slightly lower resolution than than the native one or turning off physx.
It's caused by the liquid simulation Physx uses, some of it gets stuck on a thin line of pixels at the bottom of the screen when Physx is turned on while playing on a native resolution.
This issue has apparently existed since 2012 and i'm asking if anyone after a year managed to find a fix that doesn't involve playing in window mode,lower resolution or turning off physx.
I really find Physx amazing in Borderlands 2, it's one of the few games that implemented it really good and i don't wanna turn it off.
And no it's not related to hardware failure or anything, my PC is brand new, i don't have this issue in other games, i get 60-120 FPS (i use the 120 FPS cap in the game) with all max settings, my GPU never hit abover 75c when playing Borderlands 2 and CPU never hits above 61c when playing Borderlands 2.
Intel i5 4670k 3.40 ghz
8GB DDR3 RAM Kingstom 1600 MHz
Nvidia 760 GTX 2 GB
ASrock z87 Extreme 4
Corsair TX650 Bronze rating
BenQ 1680 x 1050 monitor