A benchmark of how Borderlands 2 performs at 3840x2160 (4K) resolution with Physx Off/On when using a GTX 980 Ti.
Unsurprisingly, with PhysX set to 'High' there are massive FPS drops and stutters very frequently (especially upon firing an effect heavy weapon or general explosions).
Game being played at 4K, video rendered at 1080p.
PC Specs:
CPU: Intel i7 4790K
GPU: Zotac GTX 980 ti AMP!
RAM: HyperX FURY 8GB DDR3 1866MHZ
PSU: Seasonic M12-II EVO 620W
Storage: Western Digital 1TB Black
Sandisk SSD Plus 120GB (Stores OS)
Motherboard: Gigabyte Z97-D3H
OS: Windows 10 PRO 64 bit