5-axis milling simulations in CAM software are mainly used to detect collisions between the tool and the part. They are very limited in terms of surface topography investigations to validate machining strategies as well as machining parameters such as chordal deviation, scallop height and tool feed. Z-buffer or N-Buffer machining simulations provide more precise simulations but require long computation time, especially when using realistic cutting tools models including cutting edges geometry. Thus, the aim of this paper is to evaluate Nvidia CUDA architecture to speed-up Z-buffer or N-Buffer machining simulations. Several strategies for parallel computing are investigated and compared to CPU conventional and parallel computing, relative to the complexity of the simulation. Simulations are conducted with a professional CAD/CAM workstation equipped with a Nvidia Quadro4000 graphic card.